Calistoga City Council
October 6, 2026

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depends on multiple factors but is heavily influenced by economic considerations. Factors involved in making decisions about mitigating irrigation water shortages include availability and costs of pumping groundwater, price of alternative surface water sources, capital investments associated with maintaining permanent plantings, and status of international crop markets. (California Drought Contingency Plan, 2021) The 2024 Napa County Crop Report indicates that agricultural crop value totaled over $1 billion to the county economy in 2023. Wine grapes account for the overwhelming majority of Napa County agriculture. It should be emphasized that 2023 was above-average water year for Napa County and, thus, a single-year drought or a multi-year drought has the potential to deleteriously affect the county’s agricultural economy. In contrast, during the 2021 growing season which was accompanied by multiple heat events, top vineyards in the Napa Valley noted 10 to 30% drops in yields, stressed vines and cover crops, and reliance on reservoir water, with some growers’ reservoirs running dry.

Impacts on Groundwater
Groundwater conditions in Napa County are closely tied to both climatic variability and water use patterns, and drought conditions can significantly increase stress on the County’s aquifer systems. Reduced precipitation and runoff during drought periods limit natural recharge, while increased reliance on groundwater—particularly for agricultural and rural domestic use—can accelerate declines in groundwater levels.

Recent monitoring and analysis conducted as part of the Napa Valley Subbasin Groundwater Sustainability Plan (GSP) indicate that groundwater extraction has exceeded sustainable levels during drought conditions, resulting in measurable impacts to groundwater storage and interconnected surface water systems. During Water Years 2021 and 2022, minimum thresholds were exceeded for key sustainability indicators, including declining groundwater storage and depletion of interconnected surface water, demonstrating the sensitivity of the basin to prolonged dry conditions.

Groundwater use in Napa County is dominated by the agricultural sector, which accounts for the majority of pumping, followed by domestic, municipal, and industrial uses. Recent data indicate that total groundwater use has remained substantial across all sectors, with agriculture representing the largest share of demand. During drought conditions, reduced surface water availability often leads to increased groundwater pumping, further intensifying stress on the aquifer system. Declining groundwater levels can result in several adverse impacts, including:
▪ Reduced well productivity, particularly for shallow or low-capacity wells ▪ Increased pumping costs due to greater depths to groundwater ▪ Reduced baseflow to streams and creeks, affecting aquatic habitat and surface water availability ▪ Potential long-term reductions in groundwater storage CAL OES SUBMITTAL - JUNE 2026
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In Napa County, groundwater and surface water systems are highly interconnected. Increased groundwater pumping during drought can reduce flows in streams and rivers, particularly during late summer and fall when surface water levels are already low. This interaction is a key concern under SGMA, as reductions in interconnected surface water are considered an undesirable result that must be avoided through sustainable groundwater management.

To address these challenges, the Napa County Groundwater Sustainability Agency (NCGSA) has established a goal of reducing groundwater pumping in the Napa Valley Subbasin by approximately 10 percent from historical baseline levels as part of GSP implementation. Achieving this reduction is intended to improve groundwater storage conditions and reduce impacts to interconnected surface water systems.

Ongoing monitoring efforts—including expanded groundwater level networks, water use tracking, and hydrologic modeling—are being used to evaluate groundwater conditions and inform adaptive management strategies. These efforts support a long-term approach to balancing groundwater supply and demand, particularly under changing climate conditions.

Overall, drought conditions increase reliance on groundwater resources while simultaneously reducing recharge, creating a compounding effect that can lead to long-term declines in groundwater availability if not properly managed. Continued implementation of groundwater sustainability measures, water conservation practices, and demand management strategies will be critical to maintaining reliable groundwater supplies in Napa County.

DevelopmentTrends
Development patterns in Napa County have a direct influence on groundwater demand, recharge, and longterm basin sustainability. Growth is generally concentrated within incorporated cities and established service areas, while rural and agricultural lands—many of which rely heavily on groundwater—continue to play a significant role in overall water demand.

Groundwater use in Napa County is distributed across multiple sectors, including agriculture, domestic users, municipal systems, and commercial/industrial uses such as wineries. Recent data indicate that agricultural uses account for the majority of groundwater demand, with additional contributions from selfsupplied rural residences and small water systems. As development continues, particularly in rural and vineyard areas, groundwater demand may increase if not offset by conservation measures or alternative water supplies.

The County’s regulatory framework, including well permitting requirements and water availability analyses, requires that new development demonstrate adequate water supply and consider potential impacts to groundwater resources. Under SGMA, the Napa County Groundwater Sustainability Agency (NCGSA) is responsible for managing groundwater in the Napa Valley Subbasin to achieve long-term sustainability.

This includes implementing projects and management actions—such as groundwater pumping reductions—to balance supply and demand and avoid undesirable results.

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Development can also affect groundwater recharge. The expansion of impervious surfaces associated with residential, commercial, and infrastructure development may reduce natural infiltration, limiting the ability of groundwater basins to replenish during wet periods. In contrast, agricultural lands and open space areas can support recharge, depending on land management practices and soil conditions.

Recent planning efforts emphasize water conservation, efficiency, and demand management as key strategies for accommodating growth without increasing groundwater stress. The Groundwater Pumping Reduction Workplan identifies a range of voluntary and potential mandatory measures—including improved irrigation efficiency, water reuse, metering, and benchmarking—to reduce overall groundwater pumping across sectors. These measures are intended to support continued economic activity while maintaining groundwater sustainability.

Despite these efforts, drought conditions and climate change introduce additional uncertainty. Increased temperatures, changing precipitation patterns, and more frequent dry periods may reduce recharge and increase reliance on groundwater, particularly during peak demand periods. As a result, even modest increases in development could contribute to cumulative impacts on groundwater resources if not carefully managed.

Overall, Napa County’s development trends reflect a balance between growth and resource protection. While existing policies and SGMA implementation provide a strong framework for managing groundwater demand, continued coordination between land use planning, water resource management, and climate adaptation efforts will be essential to ensure that future development does not exacerbate groundwater depletion or compromise long-term water supply reliability.

Development Impacts
As population and economic activity increase in Napa County, overall water demand is expected to rise, placing additional pressure on water supplies during drought conditions. However, Urban Water Management Plans indicate that sufficient supplies are projected to meet future demand under both normal and dry-year scenarios. Through existing plans, policies, and regulatory requirements, new development must demonstrate adequate water availability and contribute to necessary infrastructure improvements.

These improvements, including water supply, storage, and distribution systems, are typically funded by developers through impact fees or required construction, helping to offset the potential effects of growth on water resources while maintaining long-term supply reliability.

Climate Change Impacts
Drought is a recurring hazard in Napa County and is expected to intensify under changing climate conditions. Rising temperatures, increased evapotranspiration, and more variable precipitation patterns are projected to result in more frequent and prolonged droughts, reducing surface water availability and limiting groundwater recharge. These conditions place additional stress on the Napa Valley Subbasin and other local groundwater resources, increasing reliance on groundwater pumping and reducing overall water supply CAL OES SUBMITTAL - JUNE 2026
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reliability. Climate-driven changes also have the potential to impact agricultural productivity, ecosystem health, and long-term water availability across the xounty.

Direct Impacts
Drought reduces water available for agricultural production, irrigation, and domestic use, with cascading effects on Napa County’s economy and communities. Reduced streamflow and reservoir storage can degrade water quality by concentrating pollutants and increasing temperatures, leading to higher treatment costs and operational challenges for water providers. Groundwater-dependent users, including rural residences and small water systems, may experience declining well yields or supply interruptions during prolonged dry periods.

Secondary Hazards
Drought conditions significantly increase wildfire risk by drying vegetation, extending the fire season, and increasing fuel availability across Napa County’s wildland-urban interface areas. Wildfires can further exacerbate drought impacts by damaging watersheds, reducing vegetation cover, and increasing erosion, which may impair water quality and reduce recharge capacity. In addition, reduced groundwater recharge and increased pumping during drought conditions can contribute to long-term declines in groundwater levels and reduced baseflow to streams, affecting aquatic ecosystems and surface water availability.

Public Health and Social Impacts
Drought impacts are not experienced equally across the population. As described in Section 1.5.3, lowincome households, renters, older adults, and individuals with access and functional needs may be disproportionately affected. Increased water costs, reduced supply reliability, and the need for conservation measures can place a greater burden on households with limited financial resources.

Residents in rural areas who rely on private wells are particularly vulnerable, as they may experience reduced water availability or well failure during extended drought conditions and may lack the resources to deepen wells or secure alternative supplies. Language barriers and limited access to information may also reduce the effectiveness of conservation outreach for some populations.

Drought-related conditions can also contribute to public health concerns, including reduced air quality from wildfire smoke and dust, which may exacerbate respiratory illnesses. Additionally, reduced water availability can impact sanitation, cooling, and overall health, particularly for medically vulnerable populations.

Drought Hazard Problem Statements
As part of the mitigation action identification process, the Napa County Planning Team developed areas of concern (i.e., problem statements) that summarize the county’s most pressing drought-related vulnerabilities and challenges. The problem statements were developed based on the updated risk CAL OES SUBMITTAL - JUNE 2026
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assessment and vulnerability analysis contained herein, as well as the team’s local knowledge and experience and community input. The problem statements address a broad spectrum of concerns, from direct impacts on residents and vulnerable populations to threats to critical infrastructure and long-term recovery.

These problem statements are not intended to be all-encompassing or to describe each and every issue associated with drought hazards. Instead, they highlight the most urgent concerns that can be addressed within the scope of this MJHMP. Each statement will be linked to at least one mitigation action, ensuring that identified needs are met with specific, measurable, and equitable solutions. Table 3-53 presents the drought problem statements for Napa County, along with their associated areas of concern and reference numbers for cross-linking to the mitigation actions in Table 4-4.

Table 3-53: Napa County Drought Hazard Problem Statements Problem No. Hazard Area of
Concern
Primary
Agency
Problem Description Related MA
ps-DR-NCo-41 Drought Impact Napa County Increasing average temperatures and changes in precipitation volume and timing from
climate change is decreasing the reliability of
both surface and groundwater supplies in the
County.
ma-DR-NCo-23,
ma-DR-NCo-24,
ma-DR-NCo-25,
ma-DR-NCo-26,
ma-CC-NCo-18
ps-DR-NCo-388 Drought Impact Napa County Prolonged drought stresses agricultural resources and natural ecosystems, increasing
risks of crop failure and wildfire.
ma-AG-NCo-1,
ma-CC-NCo-18
ps-DR-NCo-389 Drought Victim Napa County Drought disproportionately impacts lowerincome households with utility rate increases and those reliant on the local agriculturebased economy, including workers in the farming, food, service, and tourism industries.
ma-AH-NCo-6,
ma-AG-NCo-1,
ma-CC-NCo-18,
ma-DR-NCo-24
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3.3.7 Severe Weather Hazard Profile
Severe weather refers to any hazardous atmospheric event with the potential to cause physical damage, social disruption, or loss of life. This includes thunderstorms, downbursts, heavy rain, snowstorms, ice storms, strong winds, and other extreme weather conditions. Winter weather, such as freezing temperatures, snow accumulation, and black ice, is a key component of severe weather in Napa County, particularly in higher elevation areas.

Severe weather events can be categorized into two types. Those that affect broad geographic regions, such as Pacific Northwest windstorms or large-scale winter storms, are classified as general severe weather.

Events with a more confined area of impact, such as isolated thunderstorms or localized snow squalls, are considered localized severe weather.

Secondary & Compounding Hazards
The most significant secondary hazards associated with severe weather in the planning area include flooding, downed trees, landslides, power outages, and, in some cases, increased wildfire risk following wind-driven damage or infrastructure failure. Heavy rain can overwhelm both natural and man-made drainage systems, causing overflow and property destruction. Landslides occur when the soil on slopes becomes oversaturated and fails. Landslides are further outlined as slope failure in Section 3.3.5, while flooding is analyzed in Section 3.3.2.

Climate Change
As the world has warmed, that warming has triggered many other changes to the Earth’s climate. Changes in extreme weather and climate events, such as heat waves and droughts, are the primary way that most people experience climate change. Human-induced climate change has already increased the number and strength of these extreme events. Over the last 50 years, much of the U.S. has seen increases in prolonged periods of excessively high temperatures, heavy downpours, and in some regions, severe floods and droughts. (National Climate Assessment, 2014)
Extended frost threat is another result of climate change. In February 2018, grape growers prepared for extended frost threat, while coping with a lack of rainfall during what are typically the wettest months of the year. As climate change continues, bud break, or the appearance of shoots that will eventually yield grapes, will begin sooner, leaving the delicate new growth exposed to the hazards of frost and rain for a longer stretch of the growing season. (Lutz, 2018)
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Subhazards
For Napa County, there are specific subhazards of severe weather that are more relevant to the planning area than others. This includes high wind, heavy rain and winter weather, which are profiled as part of this section, but it also includes mention of thunderstorms and hail.

High Wind
Damaging winds are classified as those exceeding 60 mph. Damage from such winds accounts for half of all severe weather reports in the lower 48 states and is more common than damage from tornadoes. Wind speeds can exceed 100 miles per hour (mph) and can produce a damage path extending for hundreds of miles. There are seven types of damaging winds:
▪ Straight-Line Wind: Any thunderstorm wind that is not associated with rotation; this term is used primarily to differentiate from tornado winds. Most thunderstorms produce some straight-line winds as a result of outflow generated by the thunderstorm downdraft. ▪ Downdraft: A small-scale column of air that rapidly sinks toward the ground. ▪ Downburst: A strong downdraft with horizontal dimensions larger than 2.5 miles resulting in an outward burst or damaging winds on or near the ground. Downburst winds may begin as a microburst and spread out over a wider area, sometimes producing damage similar to a strong tornado. Although usually associated with thunderstorms, downbursts can occur with showers too weak to produce thunder.
▪ Microburst: A small concentrated downburst that produces an outward burst of damaging winds at the surface. Microbursts are generally less than 2.5 miles across and short-lived, lasting only 5 to 10 minutes, with maximum wind speeds up to 168 mph. There are both wet and dry microbursts:. A wet microburst is accompanied by heavy precipitation. Dry microbursts, common in places like the high plains and the intermountain west, occur with little or no precipitation reaching the ground. ▪ Gust Front: A gust front is the leading edge of rain-cooled air that clashes with warmer thunderstorm inflow. Gust fronts are characterized by a wind shift, temperature drop, and gusty winds out ahead of a thunderstorm. Sometimes the winds push up air above them, forming a shelf cloud or detached roll cloud.
▪ Derecho: A derecho is a widespread thunderstorm wind caused when new thunderstorms form along the leading edge of the boundary formed by horizontal spreading of thunderstorm-cooled air. The word “derecho” is of Spanish origin and means “straight ahead.” Thunderstorms feed on the boundary and continue to reproduce. Derechos typically occur in summer when complexes of thunderstorms form over plains, producing heavy rain and severe wind. The damaging winds can last a long time and cover a large area.
▪ Bow Echo: A bow echo is a linear wind front bent outward in a bow shape. Damaging straight-line winds often occur near the center of a bow echo. Bow echoes can be 200 miles long, last for several hours, and produce extensive wind damage at the ground.

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Heavy Rain
As storms arrive onto land from the Pacific and rise over the mountains and ridges that border the eastern boundaries of the county, the air associated with those storms cools and that cooling results in large amounts of precipitation, also known as orographic lift. The topography of Napa County provides fairly steep and well-defined watershed areas to funnel the falling rain into runoff tributaries and potentially trigger flood hazards.

Heavy rain can overwhelm both natural and man-made drainage systems, causing overflow and property destruction, and landslides can occur when the soil on slopes becomes oversaturated and fails. In Napa County, heavy rain events are common from November to April. These heavy rainstorms, often associated with an “atmospheric river” event, can deliver over one inch of rain per hour for extended time frames.

Atmospheric rivers are relatively long, narrow regions in the atmosphere (i.e., rivers in the sky) that transport water vapor, mostly from the tropics. While these rivers can vary greatly in size and strength, the average atmospheric river carries an amount of water vapor roughly equivalent to the average flow of the Mississippi River, but exceptionally strong rivers can transport up to 15 times that amount. When the atmospheric rivers make landfall, it typically releases this water vapor in the form of rain or snow. These events can disrupt travel, induce slope failures, and cause damage to life and property. A well-known referential terms for this phenomenon is the "Pineapple Express," which is a strong atmospheric river that brings moisture from the tropics near Hawaii to the West Coast. A singular or series of atmospheric rivers can cause significant damage and flooding. In 2023, more than two dozen atmospheric rivers caused two federally declared disasters. In 2024 it was one major atmospheric river that caused a federally declared disaster
Flash floods are the leading cause of heavy rain-related fatalities. Further, the presence of burn scars from previous wildfires, such as those left by the 2020 LNU Lightening Complex Fires, increases runoff and flood risks in vulnerable areas. Heavy rain and flash flooding can affect vulnerable populations such as residents living near burn scars or in low-lying areas and tourists and hikers unaware of flash flood risks in remote, mountainous areas. Impacts on property and critical infrastructure include temporary road closures as well as damage to roads, bridges, and structures. Water treatment plants and electrical substations located near waterways are particularly vulnerable.

For more information on the secondary impacts caused by heavy rain, such as flooding, refer to the Flood and Slope Failure Hazard Profiles in Sections 3.3.2 and 3.3.5, respectively.

Winter Weather
Winter weather in Napa County is primarily characterized by intense precipitation events and periodic freeze conditions occurring between November and April. The most significant winter weather hazard is associated with atmospheric river (AR) storm systems, which can deliver prolonged, high-intensity rainfall.

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resulting in rapid soil saturation, increased runoff, and elevated risk of flooding, slope failure, and infrastructure impacts.

While snowfall is extremely rare in Napa County, freeze events, including frost and occasional hard freezes, can occur during late fall, winter, and early spring. These events are particularly important due to their potential impacts on agriculture, especially vineyards and other sensitive crops.

For additional information on flooding associated with heavy precipitation events, refer to the Flood Hazard Profile (Section 3.3.2).

Other Subhazards Not Profiled
Severe Thunderstorms
Severe thunderstorms can cause both high wind and heavy rain, as well as hail and tornadoes; however, they are not highlighted as a severe weather subhazard in this profile since the primary impact of thunderstorms in Napa County is the potential spread of wildfire, which is described in more detail in Section 3.3.1.

Hail
Hail is a form of precipitation consisting of solid ice that is formed inside the updraft of a thunderstorm.

Small ice particles and supercooled water droplets that are lifted into a thunderstorm by its updraft can combine before falling into the storm’s downdraft. Then, if the updraft is strong enough, these hail stone “seeds” can be recycled back up above the freezing level in the storm to accumulate additional ice and water. It is the repeating of this process numerous times that produces larger and larger hail stones. Once a stone is too big for the updraft to hold it up in the storm, it will fall to the ground. To be categorized as severe, hail must reach a size of one inch in diameter or larger.

Hail is a dangerous product of thunderstorms, with stones as large as grapefruit in supercell thunderstorms.

Large hail can damage aircraft, homes and cars, and can be deadly to livestock and people. Hail is categorized between a quarter-inch diameter or “pea” size, up to grapefruit at four-and-a-half inches. Hail is rare in Napa County but has occurred in the past, causing significant crop damage.

Policies, Plans & Regulatory Environment
There are very few formal regulations that pertain directly to severe weather events. The California Building Standards Code, adopted by the county and other participating jurisdictions, is generally adequate to properly address development impacts from severe weather events.

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California Building Standards Code
The California Building Code (CBC), adopted by Napa County and the incorporated municipalities, is another name for the body of regulations known as the California Code of Regulations, Title 24, Part 2, which is a portion of the California Building Standards Code. The CBC incorporates by reference the International Building Code (IBC) requirements with necessary California amendments. In particular for severe weather, the CBC sets various structural loading standards, such as for high wind and snow.

Local Regulatory Environment
Napa County General Plan
The Napa County General Plan Safety Element (2023 Update) establishes goals and policies that support preparedness for severe weather events, including heavy rainfall, high wind, and extreme storm conditions that can result in flooding, power outages, and transportation disruptions. The following goal and policies are particularly relevant to severe weather hazards:
▪ Goal SAF-2: The County will be prepared in the event of a disaster to protect residents and businesses from impacts and further harm, while initiating post-disaster recovery and reconstruction as soon as feasible.
▪ Policy SAF-2.5: Protect vulnerable populations during hazard events. The County shall coordinate with municipalities, emergency response providers, and community organizations to identify individuals who may require assistance during severe weather events—including storms that result in flooding, extended power outages, or access limitations—and to mobilize resources such as transportation, shelter, and emergency services.
▪ Policy SAF-2.2 and SAF-2.6: Enhance emergency communication systems. The County supports the use of multiple communication platforms, including Alert Napa County and other emergency notification systems, to disseminate timely warnings and emergency information during severe storm events, ensuring broad reach to residents, businesses, and visitors. ▪ Policy SAF-2.3 and SAF-2.19: Maintain continuity of critical services. The County will support the structural and operational integrity of essential public services during severe weather events, including provision of backup or redundant power systems at critical facilities such as emergency shelters, pump stations, and communications infrastructure, which are particularly vulnerable during high wind and storm-related outages.
▪ Policy SAF-2.9: Disseminate emergency planning information. The County will coordinate with the agricultural sector and other organizations to provide emergency preparedness information for hazards such as severe weather and flooding, which can impact agricultural operations, workers, and associated economic activities.
▪ Policy SAF-9.1: Provide resources to vulnerable populations. The County will conduct outreach and support the establishment of accessible shelters and resources for populations most affected by CAL OES SUBMITTAL - JUNE 2026
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severe weather impacts, including those at risk from power outages, flooding, and mobility constraints.

Past Events
Severe weather events in Napa County are most commonly associated with high and strong wind events, which represent the majority of recorded incidents since 2015. According to data from the National Oceanic and Atmospheric Administration (NOAA), Napa County has experienced more than 90 severe weather events over this period, with high/strong winds accounting for the overwhelming majority of occurrences (See Table 3-54). These events have resulted in a limited number of injuries (six reported) and relatively minor documented property damage, totaling approximately $37,000.

While most wind events have not resulted in significant reported damages, they occur frequently and can cause localized impacts such as downed trees, power outages, and minor structural damage. Wind events are often associated with winter storm systems and may occur in conjunction with other hazards such as heavy rainfall or wildfire conditions.

Table 3-54. Severe Weather Events in Napa County, 2015-present Date Type Deaths Injuries Property Damage Crop Damage
2/13/2025 Strong Wind 0 0 None reported None reported
2/04/2025 High Wind 0 0 None reported None reported
12/29/2024 High Wind 0 0 None reported None reported
12/14/2024 Strong Wind 0 1 None reported None reported
11/21/2024 High/Strong Wind 0 1 $1,000 None reported
2/19/2024 Thunderstorm Wind 0 0 $1,000 None reported
2/04/2024 High/Strong Wind 0 0 None reported None reported 7/01/2023 Excessive Heat 0 0 None reported $1,000
3/21/2023 High Wind 0 0 None reported None reported
3/14/2023 High Wind 0 0 None reported None reported
3/09/2023 High Wind 0 0 None reported None reported
2/21/2023 Strong Wind 0 0 None reported None reported
1/21/2023 Frost/Freeze 0 0 None reported None reported
1/04/2023 Strong Wind 0 0 None reported None reported
12/27/2022 High Wind 0 0 None reported None reported
4/11/2022 Strong Wind 0 0 None reported None reported
3/04/2022 Strong Wind 0 0 None reported None reported
1/22/2022 High Wind 0 0 None reported None reported
7/10/2021 Excessive Heat 0 0 None reported None reported 6/07/2021 Strong Wind 0 0 None reported None reported
5/19/2021 Strong Wind 0 0 None reported None reported
3/30/2021 Strong Wind 0 0 None reported None reported
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Date Type Deaths Injuries Property Damage Crop Damage
1/26/2021 Frost/Freeze/Strong Wind 0 0 None reported None reported 1/24/2021 Strong Wind 0 0 None reported None reported
1/18/2021 High/Strong Wind 0 0 None reported None reported 12/07/2020 Strong Wind 0 0 None reported None reported
11/10/2020 Frost/Freeze 0 0 None reported None reported 11/08/2020 Strong Wind 0 0 None reported None reported
11/06/2020 Strong Wind 0 0 None reported None reported
10/25/2020 High Wind 0 0 None reported None reported
10/14/2020 Strong Wind 0 0 None reported None reported
9/08/2020 Strong Wind 0 0 None reported None reported
9/06/2020 Excessive Heat 0 0 None reported None reported 8/16/2020 Thunderstorm Wind 0 0 None reported None reported 6/05/2020 Strong Wind 0 0 None reported None reported
4/05/2020 Strong Wind 0 0 None reported None reported
3/01/2020 Strong Wind 0 0 None reported None reported
2/09/2020 Strong Wind 0 0 None reported None reported
2/02/2020 Strong Wind 0 0 None reported None reported
12/06/2019 Strong Wind 0 0 None reported None reported
11/30/2019 Strong Wind 0 0 None reported None reported
11/28/2019 Frost/Freeze 0 0 None reported None reported 11/26/2019 High/Strong Wind 0 0 None reported None reported 10/31/2019 High Wind 0 0 None reported None reported
10/29/2019 High Wind 0 0 None reported None reported
10/27/2019 High/Strong Wind 0 0 $3,000 None reported
10/23/2019 High/Strong Wind 0 0 None reported None reported 10/09/2019 Strong Wind 0 0 None reported None reported
5/16/2019 Strong Wind 0 0 $1,000 None reported
4/16/2019 Strong Wind 0 4 None reported None reported
3/05/2019 Strong Wind 0 0 None reported None reported
2/25/2019 High/Strong Wind 0 0 None reported None reported 2/13/2019 Strong Wind 0 0 None reported None reported
2/02/2019 Strong Wind 0 0 None reported None reported
1/16/2019 Strong Wind 0 0 None reported None reported
1/08/2019 Strong Wind 0 0 None reported None reported
1/05/2019 Strong Wind 0 0 None reported None reported
12/31/2018 Strong Wind 0 0 None reported None reported
12/28/2018 Strong Wind 0 0 None reported None reported
11/29/2018 High/Strong Wind 0 0 $10,000 None reported
11/22/2018 Strong Wind 0 0 None reported None reported
10/14/2018 Strong Wind 0 0 None reported None reported
10/06/2018 High Wind 0 0 None reported None reported
3/01/2018 Strong Wind 0 0 None reported None reported
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Date Type Deaths Injuries Property Damage Crop Damage
12/16/2017 Strong Wind 0 0 None reported None reported
11/27/2017 Strong Wind 0 0 None reported None reported
10/08/2017 Strong/High Wind 0 0 None reported None reported 6/11/2017 Hail 0 0 None reported None reported
4/08/2017 Extreme Cold/Wind Chill 0 0 None reported None reported 4/06/2017 Strong Wind 0 0 None reported None reported
2/20/2017 High Wind 0 0 None reported None reported
2/17/2017 High Wind 0 0 None reported None reported
2/07/2017 High Wind 0 0 None reported None reported
10/27/2016 High Wind 0 0 None reported None reported
12/22/2015 High Wind 0 0 None reported None reported
2/09/2015 Heavy Rain 0 0 None reported None reported
2/06/2015 High/Strong Wind 0 0 $23,500 None reported
Source: NOAA Storm Events Database for Napa County, including the North Bay Interior and North Bay Mountain Zones:
https://www.ncdc.noaa.gov/stormevents/
Location
Severe weather events have the potential to happen anywhere in the planning area and have historically occurred in all parts of the county; although, the types of events and their impacts are not evenly distributed.

Local topography and microclimates can cause the same storm system to produce different hazardous conditions as it moves across an area and encounters more or less moisture, various temperatures, and orographic lift, which can all influence its behavior. High wind events are most damaging to areas that are heavily wooded, while heavy rain impacts are typically seen over steep terrain and in low-lying urban areas.

Additionally, the trajectory of storm systems plays a significant factor.

Communities in low-lying areas next to streams or lakes are more susceptible to flooding. Wind events are most damaging to areas that are heavily wooded. Figure 3-41 shows the distribution of average annual rainfall in Napa County, Figure 3-42 shows the 30-year normal minimum temperature for January, and Figure 3-40 depicts average annual wind speed by power class (refer to Table 3-55).

Frequency & Probability of Future Events
Severe weather events in Napa County occur regularly and are most commonly associated with high and strong winds, heavy rainfall, and occasional hail events. Based on historical data, these events occur multiple times per year, with high/strong wind events representing the most frequent hazard type.

Since 2015, the majority of recorded severe weather incidents in Napa County have been wind-related, as summarized in Table 3-54. While heavy rain events occur less frequently as standalone severe weather entries, they contribute to cumulative impacts such as localized flooding and property damage.

Documented severe weather-related damages over this period have been relatively limited, though impacts may be underreported or captured under other hazard categories such as flooding.

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The frequency of severe weather events is expected to remain high, with multiple events occurring annually. Climate change is anticipated to increase the intensity and variability of weather patterns, including more extreme wind events and more intense precipitation associated with atmospheric river storms. These changes may increase the likelihood of higher-impact events, even if overall event frequency remains relatively consistent.

Based on historical occurrence and expected future conditions, the probability of severe weather events in Napa County is considered highly likely, with an annual probability approaching 100 percent.

Severity
The most common problems associated with severe storms are immobility and loss of utilities. Fatalities are uncommon, but can occur. Roads may become impassable due to flooding, downed trees, ice or snow, or a landslide. Crops can be damaged by below-freezing temperatures. Power lines may be downed due to high winds or ice accumulation, and services such as water or phone may not be able to operate without power.

Lightning can cause severe damage and injury. Northern California experiences lightning caused wildfires every summer.

Windstorms can be a problem in the planning area and could cause damage to utilities. The predicted wind speed given in wind warnings issued by the National Weather Service is for a one-minute average; gusts may be 25 to 30 percent higher.

Hail events can occur anywhere in Napa County. Since 2015, only one hail event has occurred, which was near Calistoga. The hail size was .25 inch.

High Wind
High wind hazards in Napa County are influenced by topography, elevation, and localized wind corridors, as illustrated in Figure 3-40 . The majority of the county experiences low to moderate average wind speeds (Wind Classes 1–2), particularly across the Napa Valley floor where terrain and vegetation reduce wind intensity. However, higher wind classes (Classes 3–4) are present in more exposed areas, including ridge lines, upper elevations, and narrow canyons, particularly in the northern and eastern portions of the county and near the Carquinez Strait in the south.

Wind is classified by the National Renewable Energy Laboratory (NREL) based on average speeds across the ground at different elevations in meters per second (m/s) and the amount of power it is capable of producing (wind power density), as provided in Table 3-55. The same wind event exhibits various speeds depending on elevation because of differences in the amount of friction encountered in proximity to the Earth’s surface; this is most often measured at 10 and 50 meters above grade, or 33 and 164 feet, respectively. According to the Rayleigh wind speed distribution principle, speed increases 3% per 1,000 meters in elevation (or 5% per 5,000 feet). Power density is measured in the amount of watts (W) that can be produced per square meter (m2) of surface area on the blades of a wind turbine.

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Table 3-55: Classes of Wind Power
Wind
Power
Class
10 m (33 ft) 50 m (164 feet)1
Wind Power Density
W/m2
Mean Speed2
m/s (mph)
Wind Power Density
W/m2
Mean Speed2
m/s (mph)
1 ≤ 100 4.4 (9.8) ≤ 200 5.6 (12.5)
2 100-150 5.1 (11.5) 200-300 6.4 (14.3)
3 150-200 5.6 (12.5) 300-400 7.0 (15.7)
4 200-250 6.0 (13.4) 400-500 7.5 (16.8)
5 250-300 6.4 (14.3) 500-600 8.0 (17.9)
6 300-400 7.0 (15.7) 600-800 8.8 (19.7)
7 >400 9.4 (21.1) >800 11.9 (26.6)
Notes:
1Vertical extrapolation of wind speed based on the 1/7 power law. 2Mean wind speed is based on Rayleigh speed distribution of equivalent mean wind power density and is for standard sea level conditions.

Source: NREL, 2007
These higher wind zones are associated with terrain-driven wind acceleration, where winds are funneled through gaps, passes, and valleys or intensified along ridgelines. As a result, while average wind speeds are generally moderate, localized areas are subject to stronger and more damaging wind events, especially during winter storm systems and offshore wind conditions.

The most common impacts of high wind events in Napa County include power outages caused by downed trees and damaged power lines, which can disrupt critical services such as emergency response, water supply, and communications infrastructure. These impacts may be localized or widespread depending on the extent and duration of the event. Strong winds can also cause structural damage to buildings, particularly roofs and lightweight structures, as well as crop damage in agricultural areas, including vineyards.

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High winds also play a critical role in wildfire behavior, as wind-driven conditions can rapidly spread fires and complicate suppression efforts. In addition, winds can contribute to soil erosion and debris movement, particularly in recently burned or disturbed areas.

Although most wind events are not life-threatening, they occur multiple times per year and represent an ongoing hazard due to their frequency and potential to disrupt infrastructure and daily activities. Wind speeds reported in forecasts are typically based on sustained (one-minute average) conditions; however, gusts may exceed these values by 25 to 30 percent, increasing the potential for damage.

Overall, the wind resource distribution in Napa County demonstrates that while much of the area experiences relatively low average wind speeds, localized high-wind zones—particularly along ridgelines and exposed terrain—present elevated risk for infrastructure damage, utility disruption, and wildfire spread.

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Figure 3-40: Napa County Annual Average Wind Speed (Power Class) CAL OES SUBMITTAL - JUNE 2026
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Heavy Rain
Heavy rain is a recurring hazard in Napa County, particularly during the winter months, and is closely associated with atmospheric river storm systems that can deliver prolonged, high-intensity precipitation.

While heavy rain alone is rarely life-threatening, it is a primary driver of secondary hazards such as flooding, slope failure, debris flows, and erosion, which can result in significant impacts to life, property, and infrastructure.

As shown in Figure 3-41 (Average Annual Precipitation), precipitation patterns in Napa County vary significantly based on topography and elevation. Higher precipitation totals, generally ranging from 35 to over 50 inches annually, occur in the northern, western, and mountainous regions of the county, including areas around Calistoga and along the Mayacamas Range. In contrast, the southern and valley floor areas, including the City of Napa and American Canyon, receive comparatively lower annual precipitation, typically in the range of 20 to 30 inches.

These spatial variations influence the distribution of heavy rain impacts. Hillside and mountainous areas, which receive higher rainfall totals, are more susceptible to soil saturation, landslides, and debris flows, particularly during prolonged storm events or in areas affected by wildfire burn scars. In contrast, urbanized and low-lying areas are more vulnerable to localized flooding and stormwater system overload, especially where drainage infrastructure is limited or undersized.

Heavy rainfall also contributes to erosion and sediment transport, which can degrade water quality and impact watershed health. Sediment and debris may accumulate in channels and culverts, reducing their capacity and increasing the likelihood of localized flooding during subsequent storm events.

Although heavy rain events occur regularly, their impacts vary depending on storm intensity, duration, and antecedent conditions such as soil moisture and recent wildfire activity. Extreme precipitation events— particularly those associated with atmospheric rivers—have the potential to produce widespread and compounding impacts across multiple hazard types, making heavy rain a key driver of overall hazard risk in Napa County.

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Figure 3-41: Napa County Average Annual Precipitation
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Winter Weather
Winter weather in Napa County is generally moderate in severity but can result in localized high-impact conditions, particularly in higher elevation areas such as the Mayacamas and Howell Mountain ranges. As shown in Figure 3-42 (30-Year Normal Minimum Temperature for January), minimum temperatures vary across the county, with colder conditions (mid-30s °F) occurring in northern and higher elevation areas, while warmer minimum temperatures (low 40s °F) are more typical in the southern valley floor and near San Pablo Bay. These temperature gradients contribute to the spatial variability of frost, freeze, and icing conditions.

Winter weather hazards in Napa County include freeze events, frost, black ice, and occasional snowfall at higher elevations. While snowfall is rare in valley areas, elevated terrain may experience light accumulation, leading to hazardous travel conditions. Cold temperatures, particularly during overnight and early morning hours, can result in ice formation on roadways, increasing the risk of vehicle accidents and temporary road closures.

The most common impacts of winter weather include transportation disruptions, power outages, and localized utility interruptions. Freezing conditions can damage infrastructure, including exposed pipes and electrical systems, while also affecting agricultural operations, particularly vineyards that are sensitive to frost and freeze events. Although widespread structural damage is uncommon, impacts to mobility and critical services are routine during cold weather events.

Winter weather is often associated with broader storm systems that also produce heavy rainfall and high winds, contributing to compound hazards such as flooding, downed trees, and slope failures. These combined conditions can exacerbate impacts, particularly in areas with limited access or infrastructure redundancy.

While fatalities are rare, extreme cold conditions can pose health risks, especially to unsheltered populations, older adults, and individuals with access and functional needs. Overall, winter weather in Napa County is best characterized as a moderate hazard with periodic high-consequence impacts, particularly in elevated and colder regions of the county.

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Figure 3-42: Napa County 30-Year Normal Minimum Temperature for January CAL OES SUBMITTAL - JUNE 2026
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Warning Time
Meteorologists can often predict the likelihood of a severe storm up to 10 days in advance. This can give several days of warning time. However, weather systems can stall or shift trajectory, thus making it difficult to predict total precipitation at specific locations. Further, some storms may come on more quickly and have only a few hours of warning time. High wind and heavy rain events can typically be predicted a few hours to a few days in advance, depending on the characteristics of the underlying severe weather system.

The ability to provide early warning for severe weather hazards in Napa County depends on monitoring systems, weather radar, and alert services. The region benefits from forecasting tools provided by the NWS, NOAA, and local emergency management agencies, which use weather stations, stream gauges, weather radar, and satellite data to issue timely warnings for hazards.

Napa County is served by the NWS San Francisco Bay Area/Monterey forecasting office located next to the Monterey Regional Airport and Naval Research Laboratory in Monterey County. The office serves a total of 11 counties throughout the San Francisco and Monterey Bay regions with a population of more than eight million residents. Radar coverage in Napa County is primarily provided by an NWS-operated, next generation WSR-88D radar (KMUX) located on Mount Umunhum southwest of the county just south of the San Jose Metro Area.

Severe Weather Vulnerability Assessment
Recent history indicates that Napa County has a high vulnerability to severe weather events due to its location and topography. Severe weather will continue to impact the people, properties, and critical facilities and infrastructure all across the county to varying degrees, causing damage and potentially threatening lives.

3.3.7.9.1 Population
It can be assumed that the entire planning area is exposed to some degree of severe weather events.

However, certain locations face greater risk due to their geographic setting and local climate conditions.

Vulnerable population groups such as older adults, people living in older housing, low-income households, individuals who speak limited English, those with serious health conditions, and residents in areas with restricted access are at the highest risk of severe weather impacts. Extended power outages can pose lifethreatening risks for individuals who rely on electricity for medical support, and cold temperatures can endanger those without reliable shelter or heating. Isolation of these populations during winter storms is a significant concern, as it may hinder access to warming centers, emergency services, and life-sustaining resources.

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Disproportionately Impacted Populations
High Wind
High wind impacts in Napa County are experienced countywide but are most severe in exposed ridgelines, hillside communities, and wildland-urban interface (WUI) areas, particularly in the northern and eastern portions of the county. Populations in these areas are more vulnerable to power outages, downed trees, and road blockages, which can disrupt access to essential services.

Rural and hillside communities often rely on limited access routes and overhead utility infrastructure, increasing the likelihood of isolation during wind events. Residents in these areas—including those in parts of Angwin, Pope Valley, and other unincorporated communities—may experience prolonged outages or delays in emergency response.

As described in Section 1.5.3, individuals with access and functional needs, including older adults, persons with disabilities, and those who are medically dependent on electricity, are particularly vulnerable to power disruptions. In addition, low-income households may have limited ability to prepare for or recover from wind-related damages, including tree removal or structural repairs. Public Safety Power Shutoff (PSPS) events implemented during high wind conditions may further compound these impacts for vulnerable populations.

Heavy Rain
Heavy rain impacts are most pronounced in areas susceptible to flooding, poor drainage, and slope instability, including low-lying valley areas and steep hillside terrain. Communities located along the Napa River corridor and its tributaries, as well as urbanized areas such as the City of Napa and American Canyon, may experience localized flooding and stormwater system overload during intense rainfall events.

Hillside and mountainous areas are particularly vulnerable to landslides and debris flows, especially in locations affected by prior wildfires. Burn scar areas have reduced vegetation and soil stability, increasing the likelihood of slope failure during heavy rain events. Residents in these areas may face elevated risk due to limited evacuation routes and potential isolation.

Populations disproportionately impacted by heavy rain include low-income households, renters, and residents in older or inadequately drained housing, who may be more susceptible to flood damage and have limited resources for recovery. Additionally, individuals with access and functional needs may face greater challenges during evacuation or service disruptions. Rural populations dependent on limited infrastructure may also experience prolonged impacts due to road closures and utility interruptions.

Winter Weather
Winter weather impacts in Napa County are generally concentrated in higher elevation areas, including the Mayacamas and Howell Mountain regions, where colder temperatures increase the likelihood of frost, CAL OES SUBMITTAL - JUNE 2026
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freezing conditions, and occasional snowfall. Populations in these areas may face hazardous travel conditions, power outages, and temporary isolation, particularly during winter storm events.

Because freezing conditions are relatively infrequent in Napa County, communities may be less prepared for impacts such as icy roadways and infrastructure disruptions. Rural residents in higher elevations may experience limited access to emergency services due to steep terrain and constrained transportation networks.

Vulnerable populations, including unsheltered individuals, older adults, and those without adequate heating or shelter, may face increased health risks during cold weather events. Additionally, individuals with limited mobility or transportation access may have difficulty reaching warming centers or essential services during extreme cold conditions.

3.3.7.9.2 Property
All property in Napa County is exposed to severe weather hazards; however, the level of risk varies based on location, structural condition, and surrounding environmental factors. Structures located in exposed areas such as ridgelines, hillside communities, and narrow canyons are more susceptible to damage from high winds, including impacts from falling trees and debris. These risks are particularly pronounced in the wildland-urban interface (WUI) and higher elevation areas, where wind speeds may be locally intensified by terrain.

Winter weather can exacerbate these vulnerabilities, particularly in higher elevation regions where freezing temperatures and occasional frost or snow events occur. Cold conditions can affect building materials, increase stress on roofs and utility infrastructure, and contribute to ice accumulation on roadways and power lines, leading to service disruptions and access limitations.

Heavy rainfall presents additional risks to property by saturating soils and increasing instability, which can result in downed trees, localized flooding, and slope failures. Properties located near steep slopes, drainage channels, or along the Napa River and its tributaries may be more vulnerable to foundation damage, erosion, and loss of access during storm events. In areas affected by prior wildfires, burn scars can further increase susceptibility to debris flows and slope instability during intense rainfall.

Agricultural properties, particularly vineyards, are also vulnerable to severe weather. High winds, heavy rain, and freeze events can damage crops, erode soils, and disrupt growing cycles, resulting in economic losses.

According to Napa County Assessor data, a substantial portion of the building stock was constructed prior to modern building codes, particularly before the adoption of updated seismic and structural standards in the late 20th century. As a result, many structures may be more vulnerable to wind, rain, and cold weather impacts if they have not been retrofitted or otherwise improved. Additionally, some properties located near waterways or on challenging terrain were developed prior to current setback and grading requirements, increasing their exposure to flooding, erosion, and slope failure during severe weather events.

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3.3.7.9.3 Critical Facilities & Infrastructure
All critical facilities are exposed to severe weather events. Facilities located on elevated terrain or within forested areas are more susceptible to wind damage, either directly or from falling trees. However, the most significant concern during severe weather is not the structural vulnerability of facilities themselves, but rather the potential for damage to roads, utilities, communications systems, and other essential infrastructure that support facility operations.

The most frequent issues during severe weather events include power outages and the resulting cascading impacts on utility systems. Downed power lines can lead to widespread blackouts, leaving entire communities without electricity. Loss of power can also disrupt phone service, water supply, and wastewater systems. Roads may become blocked or impassable due to flooding, fallen trees, or landslides triggered by heavy rainfall. High winds can bring down trees and power lines, obstructing transportation routes, delaying emergency response, and isolating communities. Snowstorms in higher elevations can significantly impact the transportation system and the availability of public safety services. Of particular concern are roads providing access to isolated areas and to vulnerable populations. Freezing of power and communication lines can cause them to break, disrupting electricity and communication.

Roadways that serve isolated areas and vulnerable populations are of particular concern, as access may be compromised during or after a storm. In addition, power and communication outages can have a disproportionate effect on seniors, individuals with medical conditions, and others who may be unable to seek help without functioning phone or transportation services. Prolonged closures of major routes can interrupt the flow of goods and services, disrupting the regional economy and delaying recovery efforts.

Large, long-lasting storms can result in significant economic losses and strain on public resources.

Facilities and infrastructure in Napa County’s rural and hillside communities are among the most vulnerable to severe weather impacts, particularly in areas with limited access and overhead utility systems. These locations may experience extended power and communication outages following major storm events. High wind events occurring in combination with heavy rainfall are especially disruptive, as saturated soils increase the likelihood of downed trees, slope instability, and debris accumulation. These conditions can damage transportation networks, obstruct waterways and drainage systems, and further delay restoration of essential services.

DevelopmentTrends
All current and future development will be affected by severe weather. However, older existing development is more susceptible than more recent development which complies with current standards.

The ability to withstand impacts lies in the consistent application and enforcement of codes and regulations for new construction. The county and other participating jurisdictions have adopted and comply with the mandated California Building Code, which is equipped to deal with the threats of severe weather events.

Land use policies identified in general plans within the planning area also address many of the secondary CAL OES SUBMITTAL - JUNE 2026
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impacts triggered by high wind or heavy rain, such as flood and landslide. However, not unlike wildfire, the proximity of residents to forested and steep slope areas places them at elevated risk of landslides and tree fall during severe weather. These localized risks, which persist despite code requirements, underscore that regulatory tools alone do not make the community fully equipped to manage all consequences of future growth and severe weather events.

Climate Change Impacts
Severe weather in Napa County—including atmospheric river storms, intense precipitation events, and high wind conditions—is expected to intensify as a result of climate change. Warmer atmospheric conditions are projected to increase the frequency and intensity of extreme rainfall, while changes in regional weather patterns may contribute to more variable and episodic storm events. These conditions can lead to greater stress on infrastructure systems, increased risk of flooding and slope failure, and more frequent utility disruptions. High wind events, particularly when occurring in conjunction with saturated soils, can further amplify damage by increasing the likelihood of downed trees and power lines.

Direct Impacts
Severe weather events can damage or overwhelm critical infrastructure systems, including stormwater conveyance, transportation networks, and overhead utilities. Intense rainfall may exceed the capacity of drainage systems, resulting in localized flooding, roadway damage, and temporary isolation of communities. High winds can cause widespread power outages and communication disruptions by damaging electrical and telecommunications infrastructure. Critical facilities—including emergency services, water and wastewater systems, and community support facilities—may be impacted by these disruptions, particularly where backup power or system redundancy is limited.

Secondary Hazards
Severe weather in Napa County frequently results in cascading and compounding impacts. Prolonged or intense rainfall can increase slope instability, leading to landslides and debris flows in hillside and wildfireaffected areas. These events can damage infrastructure, block roadways, and disrupt water and wastewater services. Storm-related debris and vegetative damage may also contribute to increased wildfire fuel loads, elevating future fire risk. Extended utility outages and infrastructure disruptions can further strain emergency response systems and delay recovery efforts.

Public Health & Social Impacts
The impacts of severe weather are not experienced equally across Napa County. As described in Section

1.5.3, low-income households, older adults, individuals with access and functional needs, and rural populations may be disproportionately affected. These populations may have limited resources to prepare for or recover from storm events, including reduced ability to invest in backup power, home hardening, or flood protection measures.

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Residents in rural and hillside areas may be particularly vulnerable due to limited access routes and greater exposure to power outages and infrastructure disruptions. Individuals who rely on electricity for medical equipment or essential services face increased health risks during prolonged outages. Additionally, language barriers and limited access to information may reduce the effectiveness of emergency communications for some populations.

Severe weather can also contribute to public health concerns, including injury risks during storm events, reduced access to emergency services, and stress associated with prolonged disruptions to housing, utilities, and transportation.

Severe Weather Hazard Problem Statements
As part of the mitigation action identification process, the Napa County Planning Team developed areas of concern (i.e., problem statements) that summarize the county’s most pressing severe weather-related vulnerabilities and challenges. The problem statements were developed based on the updated risk assessment and vulnerability analysis contained herein, as well as the team’s local knowledge and experience and community input. The problem statements address a broad spectrum of concerns, from direct impacts on residents and vulnerable populations to threats to critical infrastructure and long-term recovery.

These problem statements are not intended to be all-encompassing or to describe each and every issue associated with severe weather. Instead, they highlight the most urgent concerns that can be addressed within the scope of this MJHMP. Each statement will be linked to at least one mitigation action, ensuring that identified needs are met with specific, measurable, and equitable solutions. Table 3-56 presents the severe weather hazard problem statements for Napa County, along with their associated areas of concern and reference numbers for cross-linking to the mitigation actions in Table 4-4.

Table 3-56: Napa County Severe Weather Hazard Problem Statements Problem No. Hazard Area of
Concern
Primary
Agency
Problem Description Related MA
ps-FL-NCo-130 Severe
Weather
Threat Napa County Inadequate stormwater management practices have reduced flood storage and conveyance
capacity and exacerbate downstream and
localized flooding during heavy rain events.
ma-FL-NCo-62,
ma-FL-NCo-63,
ma-DR-NCo-26,
ma-CC-NCo-13,
ma-FL-NCo-51,
ma-FL-NCo-54,
ma-FL-NCo-57
ps-SW-NCo144Severe
Weather
Threat Napa County Intense winter storms, including heavy rain and high winds, can trigger localized flooding,
infrastructure damage, power outages, and
increase wildfire ignition risk due to downed
lines
ma-SW-NCo-81,
ma-SW-NCo-82,
ma-AH-NCo-5,
ma-AH-NCo-4,
ma-CC-NCo-15,
ma-FL-NCo-51,
ma-FL-NCo-54,
ma-FL-NCo-57
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Problem No. Hazard Area of
Concern
Primary
Agency
Problem Description Related MA
ps-SW-NCo-391 Severe
Weather
Victim Napa County Vulnerable populations, such as seniors, people living in older housing, low-income
households, unhoused persons, and those with
serious health conditions, are at the highest
risk of severe weather impacts including from
extended power outages, cold temperatures
and inadequate shelter, and isolation in areas
with limited access.
ma-AH-NCo-4,
ma-AH-NCo-6
ps-SW-NCo393Severe
Weather
Impact Napa County Winter weather brings heavy rains and, occasionally, freezing temperatures and ice,
which can have devastating impacts on grape
vines and other crops and can cause power
outages from downed trees, limbs, and power
lines.
ma-AH-NCo-4,
ma-AG-NCo-1
ps-SW-NCo394Severe
Weather
Impact Napa County Windstorms can cause downed trees, power outages, and damage to buildings and roofs,
often disrupting services and blocking access
routes.
ma-AH-NCo-4
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3.3.8 Extreme Heat Hazard Profile
Extreme heat is defined as temperatures that are much hotter and/or more humid than average for a particular location and the time of year. In Napa County, an extreme heat day that exceeds the 98th percentile of daily maximum temperatures is one at or above 90°F, and a warm night (also exceeding the 98th percentile) is one at or above about 55°F. A heat wave is an extended period of extreme heat days or warm nights, lasting days to weeks.

As a climate change-driven hazard, unusually hot and humid summer days and warm nights have become more common since the 1960s. (Bole, et al., 2018) The effects of extreme heat are amplified in urban centers such as in an around the Cities of American Canyon, Calistoga, Napa, and St.

Helena, and the Town of Yountville, with consequences for health, air quality, and utilities.

Studies show that by the end of this century, the number of days with temperatures reaching 100°F or more is projected to increase dramatically across the United States as a result of climate change. What the public now considers to be an exceptional event could become routine across much of the country. As temperatures rise and extreme heat events become longer, more severe, and more frequent, experts expect to see more health problems and deaths caused by heat.

Heat has a greater toll on human health–as measured by deaths (mortality) and negative health outcomes (morbidity)–than all other natural disasters combined. (NIHHIS, 2021) In California, a high number of heatrelated deaths occurred in 2006, when a record-breaking heat wave between July 15 and August 1 in Northern California was linked to 650 deaths and 16,000 excess emergency room visits. (California Office of Environmental Health Hazard Assessment, 2019) Heat waves and events are anticipated to increase in frequency, severity, and duration as climate change progresses in the coming decades.

Heat-related death and illness are widely regarded as preventable within the public health community; despite this, extreme heat kills over 600 people in the U.S. annually. (CDC, 2021) The following populations face specific vulnerability to heat-related illness:
▪ Seniors aged 65+, especially those who live alone;
▪ Infants and children;
▪ Low-income households;
▪ Unhoused people;
▪ Individuals with chronic underlying medical conditions; ▪ Athletes; and
▪ Agricultural and other outdoor workers.

The cumulative impacts of extreme heat events, along with smaller, longer-term differences in seasonal average temperatures, exacerbate inequities in health outcomes among already at-risk groups. (NIHHIS, 2021) Heat impacts are distributed inequitably among low-income communities of color in the United CAL OES SUBMITTAL - JUNE 2026
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States. On average, Black and Latino households are more cost-burdened, occupy denser housing stock, and have lower access to heat-coping strategies, such as air conditioning and access to green space.

Within Napa County, geographic patterns in extreme heat are mostly influenced by topography. While extreme heat days are defined by localized variation from norms, the inland valley areas tend to experience higher temperatures than coastal or mountain areas. That being said, air conditioning systems are less prevalent in the county and the population may be less adapted to higher temperatures compared to regions which regularly experience high heat events.

Although Napa County is mostly rural, there are clusters of highly urbanized areas. Urbanized areas experience higher temperatures than natural landscapes, creating localized pockets of higher temperatures known as heat islands. Roads and conventional building materials reflect less solar energy and absorb and re-emit more heat compared to trees and other vegetation. Heat islands can build throughout the day and worsen immediately after sunset as heat is slowly released from pavement and building material. The graph in Figure 3-43 demonstrates the impact of increased urbanization in relation to diurnal fluctuation of temperature extremes, with urban areas sometimes experiencing daytime highs 7°F greater than surrounding non-urban environments. (EPA, 2024)
Urban heat islands disproportionately affect low-income urban populations and people of color, communities who are more likely to occupy older, higher density housing stock with lower urban forest cover and less access to air conditioning. A 2020 study of 108 urban areas across the U.S. found that neighborhoods subjected to federal redlining policies in the first half of the 20th century, which discouraged investment in neighborhoods with high minority populations, currently experience surface temperatures approximately 5˚F higher than their non-redlined counterparts. (Hoffman, Shandas, & Pendleton, 2020) CAL OES SUBMITTAL - JUNE 2026
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Secondary & Compounding Hazards
The most significant secondary hazards associated with extreme heat events are increased public health risks from heat-related and vector-borne illness, wildfires fueled by heat-related vegetation die-off and stress, and power outages. Climate change is the main driving force behind the increase in extreme heat events and is further discussed in Section 3.3.9.

High Heat / Heat Waves
Heat waves are periods of abnormally hot weather lasting days to weeks. The number of heat waves has been increasing in recent years across the Country and locally. Climate change will continue to cause extreme heat events more often. Studies show that by the end of this century, the number of days with temperatures reaching 100°F or more is projected to increase dramatically across the United States as a result of climate change. What the public now considers to be an exceptional event could become routine Figure 3-43: Day and Night Urban Heat Island Effect Across Natural and Built Landscapes Source: U.S. Environmental Protection Agency
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across much of the country. As temperatures rise and extreme heat events become longer, more severe, and more frequent, experts expect to see more health problems and deaths caused by heat. (Prevention).

According to information provided by FEMA, extreme heat is defined as temperatures that hover 10 degrees or more above the average high temperature for the region and last for several weeks. Heat kills by taxing the human body beyond its abilities. In a normal year, about 175 Americans succumb to the demands of summer heat. According to the National Weather Service (NWS), among natural hazards, only the cold of winter—not lightning, hurricanes, tornados, floods, or earthquakes—takes a greater toll. (National Weather Service, 2020) In the 40-year period from 1936 through 1975, nearly 20,000 people were killed in the United States by the effects of heat and solar radiation. In the heat wave of 1980, more than 1,250 people died. (Disasters Are Us, n.d.)
Wildfire & Air Quality
Extreme heat often coincides with conditions favorable to wildfires and contributes to vegetation stress and mortality, fueling these hazards. Wildfires during extreme heat events can place excess health burdens on wildland firefights, impeding fire containment. Extreme heat further increases the negative effects of poor air quality from particulates like smoke as well as ozone-related sensitivities. While wildfires do not always present during extreme heat events, extreme heat always increases the risk of human health impacts to poor air quality. Climate change has a long-term negative effect on air quality metrics, including ozone. (State of California, 2018)
Power Outages
High temperatures may increase peak electricity demand beyond system capacity as residents switch on air conditioning units. Loss of power during a high heat poses a risk to human health by limiting access to air conditioning and disrupting continuous power supply for medical equipment. In California, high heat days may also coincide with conditions that trigger Public Safety Power Shutoff (PSPS) events by utility providers to curb wildfire ignition risk from faulty powerline equipment, which could disrupt residential power supply for air conditioning and at-home medical equipment.

Climate Change
The state and county have seen increased average temperatures, more extremely hot days, fewer cold nights, and shifts in the water cycle from climate change. Increased greenhouse gases in the atmosphere raises temperatures and alters seasonal temperature patterns. Effects can include changes in average temperature, the timing of seasons, and the degree of cooling that occurs in the evening. In addition to new seasonal temperature patterns, extreme events such as heat waves are projected to occur more frequently and last for longer periods of time. Though extreme heat may be moderated in the county’s coastal location, inland areas can experience much higher temperatures, and even under reduced emissions scenarios, climate change is expected to increase the frequency, intensity, and duration of extreme heat events in the Napa County region.

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Policies, Plans & Regulatory Environment
Very few formal regulations exist which pertain to extreme heat, except for workplace safety standards for outdoor workers. There are no state or local regulations pertaining to cooling technology standards for general residential buildings, but places of work, senior residential facilities, schools, and childcare centers are subject to state regulations for indoor air temperature standards. However, there is an extensive regulatory environment concerning climate change in that profile under Section 3.3.9.

State Regulatory Environment
California Outdoor Heat Illness Prevention Standard
Title 8, Section 3395 of the California Code of Regulations establishes an Outdoor Heat Illness Prevention Standard for employers of outdoor workers. Established in 2006, it requires employers to provide water and shade access; to develop a heat illness prevention plan; and provide heat illness prevention and response training to employees. Specific procedures must be followed for temperatures exceeding 80°F and 95°F.

Employers must provide shade, water, and monitor for signs of heat illness. Workers also have a right to request breaks to cool off.

Local Regulatory Environment
Napa County General Plan
The Napa County General Plan Safety Element (2023 Update) establishes goals and policies that support preparedness for extreme heat events, which are increasing in frequency and intensity due to climate change. Extreme heat poses risks to public health, energy systems, and water supply, particularly during prolonged heat waves. The following goal and policies are particularly relevant to extreme heat hazards:
▪ Goal SAF-2: The County will be prepared in the event of a disaster to protect residents and businesses from impacts and further harm, while initiating post-disaster recovery and reconstruction as soon as feasible.
▪ Policy SAF-2.5: Protect vulnerable populations during hazard events. The County shall coordinate with municipalities, emergency response providers, and community organizations to identify individuals at increased risk during extreme heat events—including older adults, medically vulnerable individuals, and those without access to cooling—and to mobilize resources such as cooling centers, transportation, and outreach services. ▪ Policy SAF-2.2 and SAF-2.6: Enhance emergency communication systems. The County supports the use of multiple communication platforms, including Alert Napa County and other emergency notification systems, to provide timely heat advisories, public health warnings, and resource information during extreme heat events.
▪ Policy SAF-2.3 and SAF-2.19: Maintain continuity of critical services. The County will support the structural and operational integrity of essential public services during extreme heat events, CAL OES SUBMITTAL - JUNE 2026
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including ensuring reliable power supply and backup systems at critical facilities such as cooling centers, medical facilities, and water infrastructure, which may experience increased demand during heat waves.
▪ Policy SAF-2.9 and SAF-2.21: Support the agricultural sector and workforce. The County will coordinate with agricultural organizations to disseminate emergency preparedness information and provide resources to protect farmworkers and outdoor workers who are particularly vulnerable to heat-related illness during extreme temperature events. ▪ Policy SAF-9.1: Provide resources to vulnerable populations. The County will conduct outreach and support access to cooling facilities, hydration resources, and emergency services for populations most at risk during extreme heat, including low-income households, renters, and individuals with limited access to air conditioning.

Past Events
Napa County has experienced a series of extreme heat events over the past several decades, with increasing frequency and intensity in recent years. These events are often associated with prolonged high temperatures exceeding 100°F, particularly in inland valley areas, and are frequently compounded by drought conditions and elevated wildfire risk. The following notable events illustrate the historical occurrence of extreme heat in Napa County and demonstrate how these conditions have contributed to impacts on public health, infrastructure, and the County’s agricultural economy. ▪ July 2011 – July 2012: Napa County experienced multiple multi-day heat events, with temperatures exceeding 100°F. These events highlighted the recurring nature of extreme heat and its impacts on agriculture and energy demand.
▪ August 2017: A prolonged and intense heatwave affected Napa County, with sustained high temperatures over several days. The event significantly impacted vineyard operations, increasing irrigation demand and stressing crops during the growing season. ▪ August – October 2020: Extreme heat and dry conditions contributed to the LNU Lightning Complex Fires, which burned over 360,000 acres regionally, including portions of Napa County. The event demonstrated the strong relationship between heat, drought, and wildfire risk, resulting in widespread damage and disruption.
▪ September 6, 2022: Napa County recorded its highest temperature on record (~115°F) during a regional heatwave. This event placed significant stress on public health systems, energy infrastructure, and vulnerable populations, and represents a benchmark extreme heat event for the County. ▪ August 2025: A multi-day extreme heat event contributed to conditions that led to the Pickett Fire, resulting in evacuations and impacts to rural communities. The event highlights the continued role of extreme heat in driving wildfire ignition and spread.

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Location
Extreme heat impacts are experienced throughout Napa County; however, the intensity and frequency of high temperatures vary spatially based on topography, elevation, and proximity to marine influences. As shown in Figure 3-44 (Napa County 30-Year Normal Maximum Temperature for July), the highest temperatures are typically concentrated in the interior valley and northern portions of the county, including areas around St. Helena and Calistoga. These areas are more susceptible to extreme heat due to their inland location and limited marine cooling influence.

In contrast, southern portions of the county, including the City of Napa and American Canyon, generally experience moderated temperatures due to the influence of San Pablo Bay, which provides cooling through marine air flow and fog intrusion. Higher elevation areas may also experience slightly lower daytime temperatures; however, they can still be subject to elevated nighttime temperatures, which contribute to heat stress. Overall, while extreme heat is a countywide hazard, the greatest exposure occurs in inland valley areas, where prolonged high temperatures and limited time cooling increase the potential for impacts to public health, agriculture, and energy demand.

Frequency & Probability of Future Occurrences
Napa County is expected to experience an increase in the frequency and intensity of extreme heat events as the climate continues to warm. Current best practices for evaluating heat risk focus on threshold-based indicators, such as the number of days exceeding 95°F and nighttime temperatures remaining above 65°F, rather than changes in average annual temperature. These metrics better reflect community exposure to hazardous heat conditions. Climate projections indicate that both extreme heat days and warm nights will become more frequent, increasing stress on public health systems, energy infrastructure, and vulnerable populations.

Based on historical trends, projected climate conditions, and the County’s risk assessment framework, the probability of extreme heat events occurring in Napa County is considered highly likely (approaching a 100 percent annual probability). As shown in the risk matrix, extreme heat is characterized by high frequency and significant potential impacts, reinforcing its classification as a priority climate-related hazard requiring continued mitigation and adaptation planning.

According to Cal-Adapt, the county will likely experience a climate change-driven increase in extreme heat days from four days per year to 22 days per year by the end of the century under a medium emissions scenario (RCP 4.5). Over the same time period, the county is also likely to see an increase in warm nights from five per year to 39. Table 3-57 explains the extreme heat event thresholds for Napa County.

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Table 3-57: Cal-Adapt Extreme Heat Terms and Thresholds Term Cal-Adapt Definition Thresholds for
Napa County
Extreme
Heat Day
Defined as a day in a year when the daily maximum/minimum temperature exceeds the 98th percentile of daily maximum/minimum temperatures based on observed historical data from 1961-1990 between April and October.

98.6°F
Warm Night
Defined as a day in April through October when daily minimum temperature exceeds the 98th historical percentile of daily minimum temperatures, based on observed data from 1961-1990 between April and October.

59.5°F
Heat Wave Defined as four consecutive days or nights above the extreme heat / warm night threshold.
3 days ≥ 98.6°F or
4 nights ≥ 59.5°F
Source: Cal-Adapt Extreme Heat Days and Warm Nights Tool CAL OES SUBMITTAL - JUNE 2026
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Figure 3-44: Napa County 30-Year Normal Maximum Temperature for July CAL OES SUBMITTAL - JUNE 2026
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Severity
Extreme heat kills by taxing the human body beyond its abilities. In a normal year, about 175 Americans succumb to the demands of heat during the summertime. In the 40-year period from 1936 through 1975, nearly 20,000 people were killed in the United States by the effects of heat and solar radiation. In the heat wave of 1980, more than 1,250 people died. (Disasters Are Us, n.d.) Although these events preceded the boom in residential use of air conditioning nationwide, they demonstrate the severity of extreme heat events when people are left without such protections.

Because the human body is capable of acclimating to local climate conditions, there is no single temperature that serves as a definition of extreme heat. This MJHMP uses the definitions set forth by CalAdapt (a data download interface provided by the CEC) for extreme heat events, warm nights, and heat waves, with descriptions and threshold values for Napa County outlined in Table 3-57.

Heat Stress Indicators
Humidity plays a large role in determining how hot conditions actually feel. As the air becomes saturated with moisture, the body loses its ability to shed excess heat through sweating. Warm and humid nights contributed to the fatal nature of the July 2006 heatwave in California. (Hulley, Dousset, & Kahn, 2020) A heat index describes what temperatures feel like to the human body, accounting for both air temperature and humidity. Figure 3-45 shows the Nation Weather Service’s (NWS) heat index classifications and calculation chart based on temperatures at different relative humidities, which are used to forecast the heat watches, warnings, and advisories for local areas described in Table 3-60. The heat index was developed for shaded, light wind conditions; it does not capture hazards from exposure to direct sunlight and hot, dry winds, which may be relevant to populations who exercise or perform physical work in direct sun.

The wet bulb global temperature (WBGT) is an indicator of heat stress for active populations that incorporates temperature, humidity, wind, solar radiation, and other weather parameters. (National Weather Service, 2022) Different heat stress indicators are useful for different applications; the WBGT may be more useful for workplace safety or athletic programs, but the heat index can help reveal community-wide vulnerabilities for inactive populations who are able to seek shade during an extreme heat event.

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Figure 3-45: Head Index Classification and Calculation
Health Impacts
The human body possesses a variety of adaptations to regulate internal temperature under warm conditions, including sweat glands, exposed skin, and walking on two legs. Above-average temperatures, even outside summer months, compromise the body’s ability to internally regulate, leading to excess illness and death. Heat-related health impacts include exacerbating existing medical conditions and acute illness related to direct exposure to high temperatures, such as heat cramps, heat exhaustion, and heat stroke, as described in Table 3-58.

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Table 3-58: Heat-Related Illnesses
Heat-Related Illness Symptoms
Heat Cramps
▪ Symptoms include muscular pains and spasms, usually in the stomach, arms, and leg muscles. ▪ Usually results from heavy exertion, such as exercising during extreme heat. ▪ Although heat cramps are the least severe of all heat-related problems, they are usually the first signal that the body is having trouble coping with hot temperatures.

Heat Exhaustion
▪ Heavy sweating
▪ Pale, clammy, moist skin
▪ Extreme weakness or fatigue
▪ Muscle cramps
▪ Headaches
▪ Dizziness or confusion
▪ Nausea or vomiting
▪ Fast and shallow breathing
▪ Fainting
Heat Stroke
▪ Flushed, hot, dry skin (no sweating)
▪ Body temperature above 103˚F
▪ Confusion or dizziness
▪ Throbbing headache
▪ Rapid or strong pulse
▪ Unconsciousness
Heat stroke is the most severe heat-related illness and occurs when a person’s temperature control system, which produces sweat, stops working. Heat stroke may lead to brain damage and death.

Many chronic medical conditions are exacerbated by high temperatures, including cardiovascular and respiratory diseases. Extreme heat days are associated with increases in hospital visits and emergency medical service (EMS) calls for heat-related illnesses along with cardiovascular and respiratory complications, renal failure, electrolyte imbalance, kidney stones, preterm birth, and negative fetal health outcomes. (Ebi, et al., 2018) Warm nighttime temperatures may also reduce the body’s ability to recover from extreme heat during the day, especially for people with underlying chronic ischemic conditions such as coronary heart disease. (Sarofim, et al., 2016) The annual number of extreme heat days and warm nights the Napa County region is expected to increase over the next century, driven by climate change, which is discussed further in its hazard profile (Section 3.3.9).

Warning Time
Meteorologists can often predict the likelihood of an extreme heat event up to 10 days in advance. This can give several days of warning time. However, meteorologists cannot predict the exact time of onset or severity of the event and some may come on more quickly or severely than expected.

Since 2014, the National Weather Service (NWS) has issued heat-related alerts for local areas based on its HeatRisk index that are then propagated in California by Cal OES. The NWS’s HeatRisk index assigns a numerical value ranging from 0 to 4 based on average historical conditions for a given local area and time of year and also accounts for the vulnerability of specific groups such as outdoor workers, children, and the elderly (Table 3-59). This tool accounts for differences in local adaptations to climate identifies unusual heat CAL OES SUBMITTAL - JUNE 2026
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(defined as the warmest 5% of temperatures) specifically for a particular date and location, resulting in daily thresholds that are unique for each location and date. For example, the index recognizes that residents of Florida are better prepared for 90°F weather than residents of Alaska.

Each HeatRisk level is accompanied by recommendations for heat protections and serves as a useful tool for planning for upcoming heat events. Based on the index and other forecasting tools, NWS issues watches, advisories, and warnings for heat events, depending on confidence and imminence factors (Table 3-60).

Table 3-59: NWS HeatRisk Categories and Related Impacts Category Risk Heat-Related Impacts
0 Green
Little / None Little to no risk from expected heat.
1 Yellow Minor Primarily affects those who are extremely sensitive to heat and without cooling/hydration. 2 Orange
Moderate Affects those who are sensitive to heat, especially those without cooling/hydration, and some health systems and industries.
3 Red Major Affects anyone without cooling/hydration as well as health systems and industries. 4 Magenta
Extreme
Rare and/or long-duration extreme heat with no overnight relief affecting anyone without cooling/hydration as well as health systems, industries, and infrastructure.

Source: National Weather Service
Table 3-60: NWS Heat Forecast Terms and Definition
Alert Type Criteria HeatRisk Category
Heat Advisory
Issued for dangerous heat conditions not expected to reach warning criteria.

Consider postponing or rescheduling outdoor activities. Stay hydrated and find a cool indoor place during the heat of the day.
2-3
(Orange to Red)
Excessive Heat
Watch
Issued when an extreme heat event is possible but its occurrence and timing are still uncertain. Reschedule outdoor activities in the coming days. Make sure that children, elderly, and pets have a place to cool off during the heat. 3-4
(Red to Magenta)
Excessive Heat
Warning
Issued when extremely dangerous heat conditions are expected or occurring.

Avoid heavy activity and direct sunlight. Stay hydrated, find a cool indoor place, and check on children, elderly, and pets.
3-4
(Red to Magenta)
Source: National Weather Service
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Extreme Heat Vulnerability Analysis
Extreme heat is an emerging and increasingly significant hazard in Napa County, with the potential to impact public health, infrastructure systems, and economic activity. This vulnerability analysis evaluates the exposure and sensitivity of key assets—including population, property, and critical facilities and infrastructure—to extreme heat conditions. The analysis considers both current conditions and projected climate trends, recognizing that rising temperatures, longer heatwaves, and warmer nighttime conditions will intensify risks over time. Understanding how extreme heat affects different segments of the community and built environment is essential for identifying vulnerabilities, prioritizing mitigation actions, and enhancing overall resilience.

3.3.8.8.1 Population
Napa County’s population is highly susceptible to extreme heat. Health impacts of extreme heat are not distributed equally, with certain groups facing compounding vulnerability to extreme heat, particularly populations such as older adults, young children, individuals experiencing homelessness, and individuals with underlying chronic diseases. Areas with higher populations of seniors and low-income households, and low cover of trees and green surfaces, face the highest exposure to extreme heat hazards. The most sensitive populations in the county reside in the areas surrounding the City of American Canyon and the City of Napa.

3.3.8.8.2 Property
Extreme heat days in Napa County are expected to reach temperatures that would affect most buildings, including older structures that are generally more vulnerable to the impacts of extreme heat. High temperatures can cause roofs and other structural components to expand and warp, weakening the structural integrity of buildings. Aging pipes are vulnerable to leaks or breakage during periods of increased water demand, as residents seek relief from heat by turning on sprinklers, filling pools, or using hoses.

In addition, agricultural crops may suffer during extreme heat events. This can result in reduced crop yields and cause a reduction in the nutritious value of the crops for the consumer. Heat events also negatively affect livestock, causing reductions in fertility, less resilience to disease, and lower production of goods such as eggs and milk. (NOAA, 2023) In Napa County, these impacts on the agricultural sector would have rippling effects from farm and food industry workers to the other sectors that support them.

3.3.8.8.3 Critical Facilities & Infrastructure
Many types of infrastructure are impacted by prolonged exposure to extreme heat including rails, roads, and aviation. High temperatures can lead to deterioration of pavement and expansion or buckling of sidewalks and roads. (Federal Highway Administration, 2013) Railroad tracks are at risk of buckling at temperatures exceeding 100˚F. (Union of Concerned Scientists, 2018) In Napa County, it is likely that temperatures will get CAL OES SUBMITTAL - JUNE 2026
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high enough to cause direct damage to most types of critical facilities or infrastructure, which may result in impacts to structural integrity, system operations, and public services.

The most common problems associated with extreme heat are loss of utilities. Public safety power shutoffs during high heat conditions combined with fire weather or increased demand on the grid from cooling systems can cause brownouts or blackouts that leave vulnerable populations without electricity and expose them heat-related illness. While those in poverty, children, and the elderly are the most at risk, no one is completely safe without the ability to stay cool. And without power, other utility systems that lack backup generation may not function. Energy demand and grid vulnerability is expected to increase across the nation and in California. (California Energy Comission, 2018) Increased energy usage and higher demand peaks can stress electricity grid system, while extreme temperatures can decrease the safe operating capacity of hardware. (US Department of Energy, 2019, p. 12) Extreme heat events are also increasingly disruptive to educational opportunities for children. Research has shown that up to 41% of schools in the country may not have proper cooling or ventilation systems, which have already caused early school dismissals and cancellations. (NOAA, 2023) Early class dismissals or cancellations due to heat put more strain on worker attendance and productivity for some parents as they scramble to find childcare, and these conditions expose children to heat-related health risks as well as lower test scores in some instances.

DevelopmentTrends
Although population growth and new development continues to occur across the county, energy efficiency and worker safety regulations help address heat-related hazards by limiting exposure, and local services include providing community cooling centers. The county’s General Plan also establishes objectives and policies aimed at protecting its communities from the impacts of extreme heat. In particular, the General Plan calls for several strategies to mitigate extreme heat hazards through activities such as urban forestry and greening to reduce urban heat islands.

California residential and building codes require residential units to have heating, but this requirement does not exist for air conditioning. The California Building Standards Code, which has been adopted by the county and other participating municipalities, includes provisions for energy efficiency that may help increase power grid resilience to peak demand during heat events.

Climate Change Impacts
Extreme heat is an emerging hazard in Napa County and is projected to become more frequent and severe as climate change accelerates. Rising temperatures, longer heatwaves, and warmer nights will increase health and safety risks, particularly in inland and mountain areas that have historically had mild microclimates and are less prepared with cooling strategies or resilient infrastructure. Extreme heat often compounds other hazards such as drought and wildfire smoke, amplifying risks for both human health and critical infrastructure.

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Direct Impacts
Extreme heat threatens public health, energy reliability, and continuity of essential services. Increased electricity demand for cooling raises the risk of brownouts or blackouts, which can disrupt public safety operations and limit access to indoor cooling. Heat also stresses critical systems such as water supply, stormwater infrastructure, and transportation networks, with prolonged events creating additional maintenance and operational challenges.

Secondary Hazards
Extreme heat often coincides with drought, wildfire, and poor air quality, creating cascading risks.

Farmworkers and outdoor laborers face simultaneous exposure to heat and wildfire smoke, heightening risks of illness, dehydration, and long-term respiratory damage. Extended periods of high temperatures also reduce nighttime cooling, placing chronic stress on vulnerable populations and increasing the likelihood of medical emergencies.

Public Health and Social Impacts
Vulnerable populations including seniors, individuals with underlying health conditions, people experiencing homelessness, low-income households, renters, and non-English speakers face the greatest risks during extreme heat events. Many households lack air conditioning, financial means to absorb higher energy costs, or reliable access to cooling centers. The County does not yet have a fully developed strategy for cooling centers or resilience hubs, and existing facilities often lack backup power, air filtration, or accessibility upgrades. As a result, those most at risk may be unable to access safe, reliable shelter during extended heat events.

The mitigation strategy addresses extreme heat by expanding access to cooling centers, improving outreach to vulnerable populations in multiple languages, strengthening monitoring of heat-related illness, and investing in resilience upgrades for public facilities. These actions aim to reduce inequities and enhance the County’s overall preparedness for a warming climate.

Extreme Heat Hazard Problem Statements
As part of the mitigation action identification process, the Napa County Planning Team developed areas of concern (i.e., problem statements) that summarize the county’s most pressing extreme heat-related vulnerabilities and challenges. The problem statements were developed based on the updated risk assessment and vulnerability analysis contained herein, as well as the team’s local knowledge and experience and community input. The problem statements address a broad spectrum of concerns, from direct impacts on residents and vulnerable populations to threats to critical infrastructure and long-term recovery.

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within the scope of this MJHMP. Each statement will be linked to at least one mitigation action, ensuring that identified needs are met with specific, measurable, and equitable solutions. Table 3-61 presents the extreme heat problem statements for Napa County, along with their associated areas of concern and reference numbers for cross-linking to the mitigation actions in in Table 4-3 and Table 4-4.

Table 3-61: Napa County Extreme Heat Hazard Problem Statements Problem No. Hazard Area of
Concern
Primary
Agency
Problem Description Related MA
ps-CC-NCo-3 High Heat Victim Napa County Extreme heat events pose risks to seniors, unhoused people, and other vulnerable
populations and to the County’s network of
cooling centers that serve them during heat
waves.
ma-CC-NCo-15,
ma-AH-NCo-4,
ma-AH-NCo-6,
ma-CC-NCo-16
ps-CC-NCo-9 High Heat Threat Napa County Increases in temperature, along with the frequency of extreme heat events and heat
waves, can adversely affect the agriculture
industry, which is a large driver of the County's
economy.
ma-CC-NCo-17,
ma-AG-NCo-1,
ma-CC-NCo-16
ps-CC-NCo-10 High Heat Impact Napa County Extreme heat events can cause power outages and damage to energy systems from increased
consumer demand and direct impacts to
facilities and infrastructure.
ma-CC-NCo-16,
ma-AH-NCo-4,
ma-AH-NCo-6,
ma-DR-NCo-26
ps-HH-NCo390High Heat Victim Napa County Farmworkers and other outdoor workers are highly exposed to extreme heat, often
compounded by drought and wildfire smoke,
which can cause illness and exacerbate
underlying respiratory and other health
conditions, with disproportionate impacts on
already vulnerable populations.
ma-AH-NCo-6,
ma-CC-NCo-15,
ma-AG-NCo-1,
ma-CC-NCo-16
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3.3.9 Climate Change Hazard Profile
Climate change is increasing the frequency, severity, and unpredictability of these disasters, intensifying long standing risks and expanding their reach into areas and populations that have not been as exposed in the past.

Throughout this plan, each hazard section includes an assessment of how climate change is expected to alter frequency, severity, and cascading impacts. This integrated approach ensures that mitigation strategies are informed by the best available climate science and address the ways climate change is making existing hazards more damaging and harder to manage.

This stand-alone section on climate change focuses specifically on agricultural impacts and sea level rise, subhazards that requires unique attention due to their long-term and, in some cases, irreversible impacts.

Unlike other hazards that can ebb and flow with weather cycles, sea level rise will steadily increase exposure for coastal communities, infrastructure, and ecosystems. Rising seas compound flood risk, accelerate coastal erosion, and threaten the stability of underground utilities, transportation corridors, and low-lying neighborhoods. Vulnerable populations, including low-income residents and those living near the shoreline, will face disproportionate impacts from displacement, loss of access, and reduced public safety.

It is important to emphasize that this MJHMP is not a climate change plan. Broader strategies to reduce greenhouse gas emissions and plan for long-term climate adaptation are addressed in the Napa Regional Climate Action and Adaptation Plan (RCAAP). Instead, this plan highlights how climate change drives hazard risk, while treating sea level rise as a stand-alone hazard due to its unique and compounding challenges.

Climate Projections: Representative Concentration Pathways (RCP) Climate change projections must account for many different variables besides greenhouse gas emissions (GHG), including changes in energy generation and land use, global and regional economic circumstances and population growth. So that research among different groups is complementary and comparable, a standard set of scenarios was developed to ensure that starting conditions, historical data, and projections are employed consistently.

These scenarios are referred to as Representative Concentration Pathways (RCP), which show the timedependent trajectories of GHG concentrations in the atmosphere and corresponding global temperature outcomes. A range of RCPs has been developed that reflect the potential timing of global action or inaction in decreasing GHGs, resulting in a lower or higher global average temperature.

Location is a key factor in determining the range of impacts from climate change. In California, the University of California Berkeley Geospatial Innovation Facility developed a platform called Cal-Adapt funded by the California Energy Commission (CEC). This platform provides tools and data on climate change across the state, including for Napa County, from global scale models that have been localized (downscaled) to 3.7-mile by 3.7-mile grids.

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Cal-Adapt data combined with information from the California Fourth Climate Change Assessment was used to model future changes in specific types of hazards consistent with the information presented in this section; projections are outlined by two separate RCPs:
▪ RCP 4.5 is a medium emissions scenario where global emissions peak by the year 2040 and then decline.
▪ RCP 8.5 is a high emissions scenario in which global emissions continue to rise through the end of the twenty-first century.

Secondary Hazards
Secondary hazards of climate change include flood, severe weather, drought, wildfire, sea level rise, extreme heat, and heavy rain events. Climate change will most likely increase the frequency at which severe weather events occur. Secondary hazards of climate change that will have the greatest impact on Napa County include flood, drought, wildfire, extreme heat and severe weather and, as such, are discussed in other hazard profiles.

Subhazards
For Napa County, there are specific subhazards of climate change that are more relevant to the planning area than others. This includes sea level rise and agricultural impacts as part of this section. These subhazards reflect the county’s unique geographic and economic conditions, including its proximity to San Pablo Bay and its reliance on a highly productive agricultural economy. Climate-driven changes such as rising water levels and increased temperature variability have the potential to affect both natural systems and economic stability. As a result, these subhazards are critical considerations for long-term resilience and adaptation planning.

Sea Level Rise
Sea level rise is the gradual increase in ocean water levels driven primarily by global climate change, including the thermal expansion of warming ocean waters and the melting of glaciers and polar ice sheets.

While global sea levels rose by less than one foot over the past century, the rate of rise is expected to accelerate throughout the 21st century as greenhouse gas concentrations continue to increase.

According to the State of California Sea Level Rise Guidance: 2024 Science and Policy Update, statewide average sea levels are projected to rise approximately 0.8 feet by 2050 and between 1.6 and 3.1 feet in the next century, depending on future emissions and risk scenarios. In Napa County, sea level is projected to rise as much as six feet by 2100. These projections are based on the best available science and incorporate both global trends and regional factors specific to the California coast.

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areas. Projected impacts include increased tidal inundation, elevated groundwater levels, and greater extent of flooding during storm events, particularly when combined with atmospheric rivers or high tide conditions. Sea level rise may also contribute to erosion of shoreline areas and loss of wetlands, which serve as natural buffers against flooding.

Sea level rise along the California coast varies due to regional influences such as ocean circulation patterns, atmospheric conditions, and local geology. These factors affect how global sea level trends are expressed locally and are important considerations for long-term planning. As sea levels continue to rise, even modest increases can significantly expand the extent and frequency of flooding in vulnerable areas.

Areas potentially exposed to sea level rise and related impacts in Napa County are further described in the Location subsection and depicted in Figure 3-46.

Agricultural Impacts
Agricultural impacts are a key subhazard of climate change in Napa County, where the local economy and land use patterns are strongly tied to winegrape production and other agricultural activities. Climate change is expected to affect agriculture through a combination of rising temperatures, changing precipitation patterns, increased frequency of extreme weather events, and shifting ecological conditions.

Temperature increases and more frequent extreme heat events can directly affect crop growth, reduce yields, and alter growing cycles. Changes in precipitation patterns, including prolonged drought and more variable rainfall, can reduce water availability for irrigation and impact soil moisture conditions. In addition, extreme weather events such as heat waves, heavy rainfall, and unseasonal frost events can cause acute damage to crops and infrastructure. (See Severe Weather and Drought Hazard Profiles for additional detail.) Agricultural Pests and Pathogens
California farmers contend with a wide range of crop-damaging pests and pathogens. Continued climate change is likely to alter the abundance and types of many pests, lengthen pests’ breeding season, and increase pathogen growth rates. For example, the pink bollworm, a common pest of cotton crops, is currently a problem only in southern desert valleys because it cannot survive winter frosts elsewhere in the state.

However, if winter temperatures rise 3 to 4.5 degrees Fahrenheit (°F), the pink bollworm’s range would likely expand northward, which could lead to substantial economic and ecological consequences for the state.

According to a 2012 California Energy Commission report “Vulnerability and Adaptation to Climate Change in California Agriculture”, change in climate can directly impact crop growth through new temperature patterns and northward shifts of pests and disease. Additionally, longer growing seasons will possibly enable pest species to complete more reproductive cycles, which can increase severity of infestations.

Temperature is not the only climatic influence on pests. For example, some insects are unable to cope in extreme drought, while others cannot survive in extremely wet conditions. Furthermore, while warming speeds up the lifecycles of many insects, suggesting that pest problems could increase. Some insects may CAL OES SUBMITTAL - JUNE 2026
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grow more slowly as elevated carbon dioxide levels decrease the protein content of the leaves on which they feed. (CalOES, 2018)
California agriculture and forests are at risk from pests and diseases that, under certain conditions, can cause severe economic, environmental, or physical harm. Table 3-62 identifies pests and diseases of concern. Agricultural disasters could also occur due to severe weather such as severe heat and freeze events. Those hazards are covered in under Severe Weather, Section 3.3.5. Drought, another potential agricultural hazard, is discussed in Section 3.3.6.

Agriculture pests and diseases can result in economic and human health disasters. For example, insect pest hazards can have a major economic impact on farmers, farm workers, packers, and shippers of agricultural products. They can also cause significant increases in food prices for consumers due to shortages. In addition, insect pests and diseases such as bark beetles, Sudden Oak Death, and Pitch Canker in trees can destroy large expanses of forest and woodland, increasing the fuel load and contributing to greater fire risk. (CalOES, 2018)
Table 3-62: California Agriculture Pests and Diseases
Dangerous To Pests and Diseases
Crops and other plants Asian citrus psyllid/-Huanglong Bing (HLB) disease, Caribbean fruit fly, glassy-winged sharp shooter/Pierce’s Disease, European Grapevine Moth, Guava fruit fly, Gypsy moth, Japanese beetle, Mediterranean fruit fly, Melon fruit fly, Mexican fruit fly, Olive fruit fly, oriental fruit fly, bark beetle Trees Polyphagous shot hole borers, Bark beetle, Gold spotted oak borer, Sudden oak death (Phythothora ramorum), Pitch canker, Emerald ash borer, Asian longhorn beetle
Livestock or poultry Foot and Mouth Disease, Highly Pathogenic Avian Influenzas (H5 & H7), Exotic Newcastle Disease
Humans Africanized honeybee, mosquito
All Red imported fire ant, Bovine Spongeform Encephalopathy, zoonotic animal viruses
Sources: cdfa.ca.gov/PHPPS/pdep/target_pests.html and
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Policies, Plans & Regulatory Environment
Successful efforts to address the challenges of climate change begin at the local level and include the implementation of environmentally sustainable practices designed to meet present and future energy needs.

State Regulatory Environment
California Green Building Standards
The County has adopted the California Green Building Standards, also known as CALGreen Code. CALGreen Code establishes regulations for green building, nonresidential and residential buildings. Topics covered in the regulations include planning and design, energy efficiency, water efficiency and conservation, material conservation and resource efficiency and environmental quality. The code also includes voluntary measures for residential, nonresidential and health facilities.

California Sustainable Communities and Climate Protection Act The Sustainable Communities and Climate Protection Act of 2008 (Sustainable Communities Act, SB 375, Chapter 728, Statutes of 2008) looks to reduce GHG emissions through coordinated transportation and land use planning with the goal of more sustainable communities. Regional targets are established for GHG emissions reductions from passenger vehicle use by the sustainable communities strategy (SCS) established by each metropolitan planning organization (MPO). The SCS is an integral part of regional transportation plans (RTP) and contains land use, housing, and transportation strategies to meet GHG reductions targets.

SB 375 also supports state requirements that a city or county general plan contains a safety element in addition to a hazard mitigation plan. AB 2140 also requires a vulnerability assessment, adaptation goals, policies and objectives, and a set of feasible implementation measures.

California Adaptation Planning Guide (APG)
California has been taking action to address climate change for over 20 years, focusing on both greenhouse gas emissions reduction and adaptation. The California APG provides guidance and support for communities addressing the unavoidable consequences of climate change.

California Coastal Commission Sea Level Rise Guidance
The California Coastal Commission Sea Level Rise Guidance provides guidance for addressing sea level rise in coastal programs and development permits. The guidance includes interpretive guidelines for LCPs and is based on updated scientific knowledge of statewide sea level rise and coastal hazards. It offers practical approaches for state agencies, local governments, and communities to enhance coastal resilience and CAL OES SUBMITTAL - JUNE 2026
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protect vital ecosystems. The guidance emphasizes the importance of sustainable adaptation strategies to manage the impacts of rising sea levels.

California Department of Food and Agriculture (CDFA)
The California Department of Food and Agriculture (CDFA) has extensive responsibilities for protecting the food supply, including protecting and responding to the invasion of plant diseases and pests. CDFA administers the statewide programs to address crop health and pest prevention and administers grant programs regarding the same. This includes the statewide exterior exclusion program, border protection stations, pest detection and emergency projects, trapping, interior exclusion quarantine programs, and Integrated Pest Control weed eradication and biological control programs.

The CDFA also administers programs to address the prevention, detection, immediate containment, and eradication of emergency animal diseases. Some animal diseases have human health implications, and all affect production and marketability of livestock and poultry. Therefore, addressing animal disease contributes to a solid foundation for economic prosperity while decreasing human health. Activities to achieve these goals include outreach and educational services, routine disease surveillance and disease investigations to detect the introduction and spread of injurious animal pests and diseases, and, when necessary, implementation of animal quarantine to control the spread of disease.

The California Conservation Corps assists in mitigating the impacts of insect pests by providing human resources to assist in state and local eradication efforts, including surveying private yards and business landscapes to detect the Glassy Winged Sharpshooter, striping citrus fruit infected by the Mexican Fruitfly, and helping eradicate the Exotic Newcastle Disease by cleaning and disinfecting backyards.

California county-level agriculture commissioners are charged with the protection of California agriculture, the environment, and the public's health and safety. These goals are accomplished through the management of programs that combine public outreach, industry, education, and enforcement actions.

County-level agricultural commissioners carry out the following programs to accomplish these aims: Pest Exclusion, Pest Detection, Pest Eradication, Pest Management, Pesticide Enforcement, Seed Certification, Nursery Inspection, Fruits, Nuts and Vegetable Standardization, Egg Inspection, Apiary Inspection, and Crop Statistics.

CDFA licenses the agricultural commissioners and maintains a liaison office to ensure close coordination with the commissioners individually and as a group. (CalOES, 2018) Invasive Species Council of California
The Invasive Species Council of California (ISCC) was established in 2009 to provide leadership and authority in state government regarding invasive species, with its primary goals being to guide efforts to keep invasive species out of the state and to eradicate incipient populations of undesirable species. ISCC is an inter-agency council chaired by the Secretary of the California Department of Food and Agriculture with members from the California Natural Resources Agency, the California Environmental Protection Agency, CAL OES SUBMITTAL - JUNE 2026
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the California Business, Transportation and Housing Agency, the California Health and Human Services Agency, and Cal OES. The ISCC has appointed a California Invasive Species Advisory Committee (CISAC) primarily tasked with making recommendations to develop and prioritize an Invasive Species Action Plan.

For more information regarding the ISCC and the CISAC, visit: http://www.iscc.ca.gov/.

Local Regulatory Environment
Successful efforts to address the challenges of climate change begin at the local level and include the implementation of environmentally sustainable practices designed to meet present and future energy needs.

Napa County Code
Napa County has designated a Winegrape Pest and Disease Control District, which levies assessments on properties containing one or more planted vineyard acres within the District to assist in the funding of inspection, detection, prevention, and education of Pierce's disease, with the goal of preventing the spread of Pierce's disease by the glassy-winged sharpshooter. (§ 3.54) Regional Climate Action and Adaptation Plan (RCAAP)
Napa County’s climate planning efforts have evolved from the 2018 Climate Action Plan (CAP) into the current Draft Regional Climate Action and Adaptation Plan (RCAAP), which provides a more comprehensive and integrated approach to addressing both greenhouse gas (GHG) reduction and climate resilience. The RCAAP expands upon earlier efforts by incorporating regional coordination, updated climate science, and a stronger focus on adaptation to climate-driven hazards such as drought, extreme heat, wildfire, and severe weather.

Consistent with State climate policy, including targets established under California Senate Bill 32 (SB 32), the RCAAP supports long-term emission reductions while also addressing the increasing impacts of climate change at the local level. The plan establishes a goal of achieving up to 85 percent reduction in GHG emissions by 2045, aligning Napa County with statewide climate objectives and international best practices.

In addition to emissions reduction, the RCAAP emphasizes climate adaptation and resilience strategies, including water conservation, wildfire risk reduction, infrastructure resilience, and protection of vulnerable populations. The plan reflects a shift from a mitigation-only approach to a more holistic framework that integrates land use planning, resource management, and hazard mitigation.

The RCAAP is currently in draft form and, once adopted, will serve as a key policy document guiding Napa County’s response to climate change and supporting implementation of strategies identified in the Hazard Mitigation Plan.

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Napa County General Plan
The Napa County General Plan establishes a comprehensive policy framework that directly supports the County’s Climate Change Profile and associated subhazards, including extreme heat, drought, severe weather, wildfire, sea level rise, and agricultural impacts. The General Plan integrates climate change considerations primarily through the Conservation and Safety Elements, emphasizing greenhouse gas (GHG) reduction, resource conservation, and adaptive management strategies to address evolving climate risks.
▪ Goal CON-15 establishes the County’s commitment to reducing local GHG emissions that contribute to climate change, aligning with broader State and regional climate objectives. This goal supports long-term mitigation of climate-driven hazards such as extreme heat, drought, and wildfire by addressing underlying emissions sources.
▪ Policy CON-65 provides a comprehensive framework for reducing and offsetting GHG emissions while enhancing carbon sequestration across natural, agricultural, and urban systems.

Implementation measures—including preservation of agricultural lands, promotion of urbancentered growth, and support for alternative transportation—reduce exposure to climate-related hazards by limiting sprawl, protecting open space, and maintaining ecosystem services that buffer against drought, flooding, and extreme heat. Additionally, requirements to evaluate GHG emissions in discretionary projects ensure that new development considers both mitigation and long-term climate risk.
▪ Policy CON-73 establishes an adaptive management approach to climate change by requiring ongoing monitoring of ecological and environmental conditions, including sea level rise, water resources, agriculture, and local microclimates. This policy directly supports the Climate Change Profile by recognizing the dynamic nature of climate hazards and the need to adjust policies and operations over time in response to observed and projected impacts.

Collectively, these goals and policies reinforce the County’s ability to address climate-related subhazards by:
▪ Supporting drought resilience through water resource monitoring and conservation, ▪ Reducing extreme heat and wildfire risk through land use and vegetation management strategies, ▪ Addressing sea level rise and flooding through long-term environmental monitoring and planning, and
▪ Protecting agricultural viability, which is particularly sensitive to climate variability.

The General Plan’s emphasis on urban-centered growth, agricultural preservation, and environmental stewardship provides a foundational framework for reducing vulnerability to climate change.

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Past Events
Climate change is currently affecting California and Napa County, where global mean sea level has risen by as much as seven inches along the coast over the last century, increasing pressure on the state’s and county’s infrastructure, water supplies, and natural resources. The state and county have seen increased average temperatures, more extreme hot days, fewer cold nights, shifts in the water cycle with less winter precipitation falling as snow, and snowmelt running off sooner in the year (California Natural Resources Agency, 20189).

There is consensus among the world’s leading climate change scientists that human-generated emissions of heat-trapping greenhouse gases (GHGs) are the primary cause of the warming trend. Projections indicate that atmospheric concentrations of GHGs will continue to increase throughout this century. Data describing atmospheric GHG concentrations over the past 800,000 years demonstrates that concentrations of carbon dioxide (CO2), the primary anthropogenic GHG, have increased substantially since pre-industrial times, driven largely by economic and population growth, and are now higher than ever. This has led to atmospheric concentrations of carbon dioxide, methane and nitrous oxide that are unprecedented in at least the last 800,000 years. Their effects, together with those of other anthropogenic drivers, have been detected throughout the climate system and are extremely likely to have been the dominant cause of the observed warming since the mid-20th century. (IPCC,2014).

The Intergovernmental Panel on Climate Change (IPCC) described potential global emission scenarios for the coming century. The scenarios vary from a best-case, characterized by low population growth, clean technologies, and low GHG emissions; to a worst-case, wherein high population and fossil-fuel dependence result in extreme levels of GHG emissions. Continued emission of greenhouse gases will cause further warming and long-lasting changes in all components of the climate system, increasing the likelihood of severe, pervasive, and irreversible impacts for people and ecosystems. Limiting climate change would require substantial and sustained reductions in greenhouse gas emissions which, together with adaptation, can limit climate change risks.

Many aspects of climate change and associated impacts will continue for centuries, even if anthropogenic emissions of greenhouse gases are stopped. The risks of abrupt or irreversible changes increase as the magnitude of the warming increases (IPCC 2014) Our natural, economic, and cultural systems are closely tied to the climate. Significant changes in the climate will impact the way people live: the food we grow, our health and safety, the availability of water, our economy, wildlife and vegetation, and many other aspects of our lives.

Sea Level Rise
Historic records from the San Francisco tidal gage, CA Station ID: 9414290, show that the sea level in the San Francisco Bay has risen eight inches from 1897 to 2006. Similarly, water level measurements from the tidal gage at Port Chicago, CA Station ID: 9415144, show an increase in mean sea level of 2.08 millimeters a year, which is equivalent to a change of 8.6 inches in 100 years.

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Agricultural Impacts
Napa County’s agricultural sector, particularly its globally significant viticulture industry, has experienced a range of hazard events that are increasingly linked to climate variability and long-term climate change.

While traditional agricultural disasters such as pest infestations have occurred historically, recent decades have seen a shift toward climate-driven impacts, including extreme heat, prolonged drought, and wildfirerelated effects.

Extended drought conditions, most notably during the 2012–2016 statewide drought and subsequent dry periods, significantly stressed vineyard operations and reduced water availability for both irrigation and groundwater recharge. These conditions led to increased reliance on groundwater, heightened concerns regarding basin sustainability, and impacts to crop yields and vine health.

Extreme heat events have also caused measurable agricultural losses. Heatwaves in 2017, 2020, and 2022 resulted in sunburn damage to grape clusters, reduced yields, and altered harvest timing. Elevated nighttime temperatures further affected grape quality by disrupting ripening cycles, with implications for wine production and market value.

Wildfire events, including the 2017 North Bay Fires and the 2020 LNU Lightning Complex, had substantial indirect impacts on agriculture. In addition to direct damage to vineyard infrastructure, smoke exposure resulted in widespread “smoke taint,” rendering some grape harvests unusable and causing significant economic losses. These events were exacerbated by prolonged drought and extreme heat, which contributed to fuel dryness and fire intensity.

Climate-related shifts have also influenced pest and disease dynamics. Warmer temperatures and changing precipitation patterns can expand the range and lifecycle of agricultural pests and pathogens, increasing management costs and risks to crop productivity.

Collectively, these events demonstrate that agricultural impacts in Napa County are increasingly driven by the interaction of multiple climate-related hazards. The growing frequency and severity of drought, heat, and wildfire events underscore the need for continued adaptation strategies to protect agricultural resources, sustain economic productivity, and maintain the long-term viability of the County’s agricultural sector.

Location
The effects of climate change are not limited by geographical borders. Napa County, the State of California, the United States, and the rest of the world are all at risk of climate change. As such, the entire county is at risk to the effects of climate change.

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Sea Level Rise
Sea level rise impacts in Napa County are geographically concentrated in the southern portion of the county, particularly in low-lying areas adjacent to San Pablo Bay and along the lower reaches of the Napa River and its tidal tributaries. As shown in Figure 3-46, the areas most vulnerable to inundation are located in and around American Canyon and the southern Napa Valley, where elevations are lowest and tidal influence is greatest.

While sea level rise is often associated with coastal environments, its effects in Napa County extend beyond the immediate shoreline. Rising bay water levels can increase tidal backwater effects, leading to higher water levels further upstream along the Napa River system. In addition, sea level rise may contribute to elevated groundwater levels in low-lying areas, increasing the potential for flooding, reduced drainage capacity, and impacts to infrastructure even outside of directly inundated zones.

The figure indicates that exposure increases progressively under higher sea level rise scenarios, with areas currently experiencing minimal or no inundation becoming susceptible under intermediate and extreme projections. These impacts are most pronounced in flat, low-elevation with limited natural drainage and in areas with existing flood risk.

Although the northern and upland portions of Napa County are not directly exposed to coastal inundation, they may still experience indirect impacts, including changes in watershed dynamics, downstream flooding conditions, and ecological shifts. Overall, sea level rise in Napa County is a spatially concentrated hazard with expanding inland influence over time, primarily affecting southern and tidally influenced areas.

Agricultural Impacts
Napa County’s Agricultural Preserve, established in 1968, plays a central role in shaping the County’s land use patterns and exposure to climate-related hazards. The Preserve encompasses much of the valley floor in unincorporated areas between the City of Napa and Calistoga and was the first program of its kind in the nation. Initially protecting approximately 26,000 acres of farmland, the Agricultural Preserve has expanded to over 31,600 acres, with no lands removed since its establishment.

More broadly, Napa County spans over 500,000 acres, of which approximately 90 percent is designated as Agriculture, Watershed, and Open Space. Within this area, roughly 46,000 acres are in winegrape production (Napa Dep't of Ag./ Sealer of Weights & Measures, 2017), reflecting the County’s strong reliance on agriculture as a primary land use and economic driver. This extensive agricultural landscape, particularly along the valley floor, overlaps with areas potentially influenced by flooding, groundwater changes, and sea level rise, highlighting the importance of considering agricultural resources within the County’s climate change vulnerability and adaptation planning.

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Figure 3-46: Predicted Sea Level Rise Map
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Frequency & Probability of Future Occurrences
In terms of how likely and quickly impacts will occur, temperature related impacts are the most likely nearterm climate change exposure facing the county and should be addressed and prioritized in future adaptation planning efforts. While sea level rise has a high certainty rating and is already occurring, its onset is not expected to occur until closer to the end of the century in terms of changes in areas already vulnerable to flooding or causing permanent inundation in tidally-influenced areas of the county.

Addressing increases in flooding and wildfire risk have mid-term onsets and should be prioritized accordingly. (Napa County Climate Action Plan, 2018)
Climate change is one of the few natural hazards where the probability of occurrence is influenced by human action. In addition, unlike earthquake and floods that occur over a finite time period, climate change is an ongoing hazard. The California Climate Adaptation Strategy delineated how climate change may impact and exacerbate natural hazards in the future, including wildfires, extreme heat, floods, drought, and levee failure:
▪ Climate change is expected to lead to increases in the frequency, intensity, and duration of extreme heat events and heat waves in Napa County and the rest of California, which are likely to increase the risk of mortality and morbidity due to heat-related illness and exacerbation of existing chronic health conditions. Those most at risk and vulnerable to climate-related illness are the elderly, individuals with chronic conditions such as heart and lung disease, diabetes, and mental illnesses, infants, the socially or economically disadvantaged, and those who work outdoors. ▪ Higher temperatures will melt the Sierra snowpack earlier and drive the snowline higher, resulting in less snowpack to supply water to California users.
▪ Droughts are likely to become more frequent and persistent in the 21st century. ▪ Intense rainfall events, periodically ones with larger than historical runoff, will continue to affect California with more frequent and/or more extensive flooding. ▪ Storms and snowmelt may coincide and produce higher winter runoff from the landward side, while accelerating sea-level rise will produce higher storm surges during coastal storms. Together, these changes will increase the probability of levee and dam failures in the Sacramento-San Joaquin Delta.

Droughts and warmer and more severe weather can be expected to increase wildfire through fuel hazards and ignition risks. These changes can also increase plant moisture stress and insect populations, both of which affect forest health and reduce forest resilience to wildfires. An increase in wildfire intensity and extent will increase public safety risks, property damage, fire suppression and emergency response costs to government, watershed and water quality impacts, vegetation conversions, and habitat fragmentation.

Sea Level Rise
Sea level rise is considered a gradual, long-term hazard that will continue to occur and intensify over time as a result of climate change. Unlike episodic hazards, sea level rise is not defined by discrete events but by CAL OES SUBMITTAL - JUNE 2026
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a progressive increase in baseline water levels, which in turn increases the frequency, extent, and duration of coastal and tidal flooding.

According to the State of California Sea Level Rise Guidance: 2024 Science and Policy Update, statewide average sea levels are projected to rise approximately 0.8 feet by 2050 and between 1.6 and 3.1 feet by 2100, with higher-end scenarios possible under extreme conditions. These projections indicate that impacts currently associated with rare storm events will become increasingly common or chronic over time, particularly in low-lying and tidally influenced areas.

In Napa County, the effects of sea level rise will be most evident along San Pablo Bay and the lower Napa River, where rising water levels will increase the likelihood of frequent tidal inundation, backwater flooding, and elevated groundwater conditions. Areas that currently experience flooding only during extreme high tides or storm events may, under future conditions, experience regular or seasonal flooding.

While the onset of sea level rise impacts is gradual, the probability of experiencing its effects increases steadily over time. By mid-century and beyond, sea level rise is expected to transition from an emerging concern to a persistent and recurring condition in vulnerable areas of the County.

Based on current projections and the County’s risk assessment framework, the probability of sea level rise impacts occurring in Napa County is considered highly likely (approaching a 100 percent annual probability over the planning horizon). This reflects both the certainty of continued sea level rise and the increasing likelihood that its effects will be experienced on a regular and recurring basis, particularly when combined with storm events and high tide conditions.

Agricultural Impacts
Agricultural impacts associated with climate change are expected to increase in both frequency and severity over time as temperature, precipitation variability, and extreme weather conditions continue to shift. Unlike singular hazard events, agricultural impacts are typically the result of compounding and interacting climate stressors, including extreme heat, prolonged drought, changing precipitation patterns, and wildfire.

In Napa County, climate projections indicate a continued rise in average and extreme temperatures, more frequent and intense heat waves, and greater variability in water availability. These conditions are expected to increase the likelihood of crop stress, reduced yields, altered growing seasons, and increased irrigation demand, particularly for high-value winegrape production. Additionally, warmer conditions may contribute to the expansion of pests and plant diseases, further increasing risks to agricultural productivity.

Drought conditions are also projected to occur more frequently and with greater intensity, reducing surface water availability and increasing reliance on groundwater resources. At the same time, shifts in precipitation patterns, including more intense but less frequent storm events, may reduce effective groundwater recharge and increase runoff, limiting water availability during critical growing periods.

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Wildfire risk, which is closely linked to prolonged heat and dry conditions, is also expected to increase.

Wildfires can have both direct impacts on agricultural lands and indirect impacts such as smoke exposure, which can damage crops and reduce marketability. These compound hazards further elevate the overall risk to Napa County’s agricultural sector.

Based on current climate projections and observed trends, the probability of agricultural impacts related to climate change in Napa County is considered highly likely (approaching a 100 percent annual probability).

While the specific nature and severity of impacts may vary from year to year, the underlying drivers—rising temperatures, water stress, and increased hazard interaction—are expected to result in recurring and progressively more significant effects on agricultural production over the planning horizon.

Severity
The State of California has been proactively addressing climate change for over two decades through policies and planning frameworks that integrate greenhouse gas (GHG) reduction and climate adaptation strategies. The California Adaptation Planning Guide (APG) provides a standardized, science-based framework for local governments to assess climate vulnerability, evaluate risk, and develop adaptation strategies tailored to regional conditions.

Consistent with the 2020 APG guidance, climate change impacts are evaluated based on exposure, sensitivity, and adaptive capacity, which together determine overall vulnerability and severity. Napa County is located within the San Francisco Bay Area climate region, which is characterized by a Mediterranean climate, strong coastal influences, and complex topography ranging from baylands to inland valleys and mountainous terrain. These geographic characteristics contribute to high variability in climate exposure, resulting in differing hazard intensities across the county.

Within this regional context, Napa County is expected to experience increasing severity of climate-related impacts, particularly those associated with temperature extremes, water availability, and compound hazard events. As identified in the APG and supporting climate assessments, the most relevant climate stressors for Napa County include:
▪ Increasing average and extreme temperatures
▪ Changes in precipitation patterns and greater variability ▪ Increased frequency and intensity of extreme weather events ▪ Sea level rise affecting tidally influenced areas (e.g., southern Napa County) ▪ Increased risk to public health, particularly from heat and air quality ▪ Impacts to agriculture, including crop viability and productivity ▪ Increased inland flooding and watershed instability
These stressors are not independent; rather, they interact to amplify overall hazard severity, particularly where multiple systems (e.g., water supply, agriculture, and infrastructure) are interdependent.

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Table 3-63: Summary of Cal-Adapt Climate Projections for the Bay Area Region Climate
Variable Projected Change Implications for Napa County
Temperature Increase of approximately 4°F to 6°F by
late century, with greater increases
during summer months
Increased extreme heat events, higher
evapotranspiration, stress on water supply
and agriculture
Precipitation High variability with modest overall
declines (approximately 1–5 inches
annually by late century)
Increased drought risk, reduced
groundwater recharge, and more variable
water supply
Sea Level
Rise
Approximately 1.6 to 3.1 feet by 2100
(statewide guidance)
Increased flooding and groundwater
impacts in southern Napa County (e.g., Napa
River and San Pablo Bay areas)
Heat Waves Significant increase in frequency,
duration, and intensity; up to 6–10
additional heat waves annually by late
century
Elevated public health risks, increased
energy demand, and impacts to outdoor
labor and agriculture
Wildfire Risk Increasing risk due to hotter, drier
conditions and fuel accumulation
Greater likelihood of large, high-severity
wildfires affecting watershed health and air
quality
Source: Cal-Adapt; California Adaptation Planning Guide (2020); California Climate Change Assessment Sea Level Rise
Sea level rise poses a moderate but increasing long-term hazard in Napa County, with the most significant impacts concentrated in low-lying, tidally influenced areas near the Napa River and San Pablo Bay. Rising sea levels contribute to more frequent and extensive tidal inundation, particularly when combined with storm surge, atmospheric river events, and high tide conditions. These combined factors increase the likelihood of coastal flooding, shoreline erosion, and elevated groundwater levels, which can degrade infrastructure performance and accelerate landward flood extents.

According to the State of California Sea Level Rise Guidance: 2024 Science and Policy Update, sea levels are projected to rise approximately 0.8 feet by 2050 and between 1.6 and 3.1 feet by 2100. These increases will significantly expand the area exposed to periodic and permanent inundation.

In Napa County, sea level rise threatens critical public and private assets, including wastewater treatment facilities, sewer conveyance systems, transportation corridors, and essential facilities such as emergency response services and detention facilities. Residential and commercial properties in southern Napa County, particularly in and around American Canyon and bay-adjacent areas, face increasing risk of chronic CAL OES SUBMITTAL - JUNE 2026
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flooding and infrastructure disruption. Over time, these impacts are expected to intensify, especially when combined with other climate-driven hazards such as extreme precipitation and storm events.

Agricultural Impacts
Climate change poses a high-severity risk to Napa County’s agricultural sector due to the combined effects of extreme heat, drought, changing precipitation patterns, and wildfire. These stressors directly affect crop productivity, water availability, and long-term agricultural viability, particularly for the County’s winegrape industry, which is highly sensitive to temperature and climate variability.

Rising temperatures and more frequent heat waves can result in crop stress, sunburn damage, reduced yields, and altered growing cycles, while elevated nighttime temperatures can negatively affect grape quality and harvest timing. Prolonged drought conditions further increase severity by reducing surface water supplies and increasing reliance on groundwater, which may already be under stress. In addition, shifts in precipitation patterns—characterized by more intense but less frequent storms—can reduce effective soil moisture and groundwater recharge.

Wildfire represents a significant compounding factor, with both direct damage to agricultural lands and indirect impacts such as smoke taint, which can render crops unmarketable. Climate change may also contribute to the expansion of pests and plant diseases, increasing management costs and production risks.

Given Napa County’s economic reliance on agriculture and the sensitivity of specialty crops to climate conditions, these impacts represent a critical threat to both economic stability and land use sustainability.

The severity of agricultural impacts is expected to increase over time as climate conditions continue to shift and compound hazard interactions become more pronounced.

Warning Time
As this section as described, many existing hazards could be intensified as a result of climate change, decreasing warning times and exacerbating impacts. Warning times are discussed under the various other hazards. Other climate change impacts are more long-term; scientists have a high confidence in predicting the rise in global temperatures and have reached a consensus on the future impacts of climate change and the time frame in which they will occur.

Identifying the presence of insects and pests in agricultural lands is the most important step in warning for an agriculture disaster. Once identified, preventing the insects and pests from establishing a population is critical. Communication between farmers to warn each other of the presence of invasive pests and insects so that appropriate measures can be taken to prevent them from establishing a population and negatively impacting crops.

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Climate Change Vulnerability Assessment
This section evaluates Napa County’s vulnerability to the direct and indirect impacts of climate change, with particular emphasis on sea level rise, which presents a spatially distinct and measurable risk within the planning area. Other climate-related impacts, such as extreme heat, drought, wildfire, and severe weather, are addressed in detail within their respective hazard profiles, reflecting their role as primary and interacting hazards.

In addition to physical hazards, climate change may exacerbate secondary impacts to the agricultural sector, including the spread of pests and diseases that can affect both economic productivity and, in some cases, public health. Consistent with guidance from Cal OES, mitigation of these risks includes the use of integrated pest management strategies and adaptive agricultural practices.

This vulnerability assessment considers how climate-driven changes may affect people, property, infrastructure, and natural systems, with a focus on identifying areas and populations most at risk and informing targeted mitigation and adaptation strategies.

Napa County’s vulnerability to climate change is characterized by both spatially defined hazards, such as sea level rise (SLR), and system-wide impacts, such as agricultural sensitivity to changing climate conditions. This section differentiates between these two exposure types: (1) mapped hazard footprints, where risk can be geographically delineated, and (2) distributed vulnerabilities, where impacts occur across broad areas without a single defined hazard boundary.

3.3.9.9.1 Population
Climate change is expected to have increasing public health impacts across Napa County due to rising temperatures, wildfire smoke exposure, and extreme weather events. However, exposure to sea level rise is geographically limited and measurable. As shown in Figure 3-48 (Population Exposure to Sea Level Rise) and summarized in Table 3-65, approximately 1,450 residents (6.46%) in the unincorporated county are exposed under a 6-foot SLR scenario.

The mapped SLR hazard footprint demonstrates that population exposure increases incrementally with higher water levels, but overall remains a relatively small proportion of the County’s total population. This reflects the localized nature of SLR risk, primarily affecting southern Napa County near San Pablo Bay and the lower Napa River.

In contrast, agricultural and climate-related health impacts are not confined to a mapped footprint. Extreme heat, wildfire smoke, and drought affect populations across the county, particularly outdoor workers, seniors, and low-income households, many of whom are employed in agriculture. These populations may face cumulative exposure to multiple climate stressors, even if they are not located within the SLR hazard area.

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Figure 3-47: Exposure Summary – Napa County Sea Level Rise Risk CAL OES SUBMITTAL - JUNE 2026
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In Napa County, vulnerable populations are often concentrated in areas with higher exposure to environmental stressors, including extreme heat, wildfire risk, and potential flooding in low-lying areas.

Figure 3-48 illustrates areas where populations may be more exposed to sea level rise and associated hazards, highlighting the intersection of physical risk and social vulnerability.

Figure 3-48: Napa County Population Exposure to Sea Level Rise Table 3-64: Napa County Population Exposure to Sea Level Rise Total Population
Unincorporated County 22,468
Sea Level Rise (Feet Above Mean High Water) Population Count % of Total 0ft - MHW 788 3.51%
1ft 1,044 4.65%
2ft 1,256 5.59%
3ft 1,318 5.86%
4ft 1,385 6.17%
5ft 1,434 6.38%
6ft 1,450 6.46%
788
1,044
1,256
1,318
1,385 1,434 1,450
-
200
400
600
800
1,000
1,200
1,400
1,600
0ft - MHW 1ft 2ft 3ft 4ft 5ft 6ft
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Disproportionately Impacted Populations
Climate change impacts in Napa County are not experienced uniformly. As identified in Section 1.5.3, certain populations are disproportionately vulnerable due to a combination of age, health status, occupation, income, language access, and housing conditions. Approximately 17% of the County’s population is age 65 or older, representing about 18,777 households, and 33% identify as Hispanic or Latino, indicating a substantial portion of residents may face elevated sensitivity to climate-related hazards.

Extreme heat represents one of the most significant public health risks associated with climate change.

Older adults are particularly vulnerable to heat-related illness, including heat exhaustion and heat stroke, as well as exacerbation of pre-existing respiratory and cardiovascular conditions. Many seniors may live alone or have limited mobility, increasing challenges related to evacuation, access to cooling, and recovery during prolonged extreme heat events and associated power outages.

Napa County’s agricultural workforce, which is largely Hispanic and includes many low-income and Spanish-speaking individuals, faces elevated exposure to climate hazards due to the nature of outdoor labor.

Climate change is expected to increase the frequency and intensity of extreme heat and wildfire smoke events, which can reduce productivity and, in severe cases, lead to illness, injury, or death. Language barriers and limited access to resources may further reduce the effectiveness of emergency communications and preparedness efforts.

Additional vulnerable groups include renters and lower-income households, who may have limited ability to implement structural mitigation measures or access post-disaster recovery resources. Individuals with access and functional needs, including those with disabilities or limited transportation, may also face increased challenges during evacuations or extended service disruptions. These disparities highlight the importance of incorporating equity-focused strategies into climate adaptation and hazard mitigation planning.

Sea Level Rise
Approximately 6.46% of the unincorporated County population (1,450 residents) is currently located within the mapped sea level rise hazard area under a 6-foot scenario, as shown in Figure 3-48 and Table 3-71. While this represents a relatively small portion of the overall population, exposure increases incrementally with rising water levels, and the geographic extent of flooding is expected to expand over time.

Populations located in low-lying areas of southern Napa County, particularly near San Pablo Bay and the lower Napa River, may face increasing risk from tidal inundation, storm-related flooding, and elevated groundwater conditions. These impacts are expected to become more frequent and persistent as sea levels continue to rise.

Factors that increase vulnerability to sea level rise include limited access to preparedness information, transportation, healthcare, and insurance, as well as socioeconomic characteristics such as income, language proficiency, and housing tenure. Linguistically isolated populations may face additional CAL OES SUBMITTAL - JUNE 2026
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challenges in receiving and understanding emergency warnings and recovery information, while renters and lower-income households may have fewer resources to prepare for or recover from recurrent or chronic flooding conditions.

Agricultural Impacts
Agricultural impacts related to climate change pose a significant risk to both the local economy and populations directly employed in the agricultural sector. Napa County’s agricultural production value exceeds $1 billion annually, and the industry is highly sensitive to changes in temperature, water availability, and extreme weather conditions.

Unlike sea level rise, which affects a defined geographic area, agricultural impacts occur across the entire County, particularly within the valley floor and vineyard areas Climate change is expected to increase the frequency and intensity of extreme heat, drought, and wildfire, all of which can disrupt crop production, alter growing conditions, and affect long-term agricultural viability.

These impacts disproportionately affect agricultural workers, who are often exposed to hazardous environmental conditions such as extreme heat and wildfire smoke. Many of these workers may have limited access to healthcare, financial resources, and workplace protections, increasing their vulnerability to climate-related hazards.

In addition to economic and workforce impacts, climate change may influence the distribution and prevalence of agricultural pests and vector-borne diseases, which can affect both crop productivity and public health. Changing environmental conditions may increase the presence and range of diseasecarrying insects, requiring ongoing monitoring and adaptive management strategies to protect agricultural resources and surrounding communities.

3.3.9.9.2 Property
Sea level rise presents a quantifiable risk to property within a defined hazard footprint. As shown in the Sea Level Rise Exposure Map and summarized in Table 3-65 (Parcel Exposure), approximately 155 parcels (1.1%) are exposed under a 6-foot SLR scenario, representing over $137 million in total property value.

The mapped hazard area is concentrated in low-lying of southern Napa County, including areas near American Canyon and the Napa River corridor. While current exposure is relatively limited, the data demonstrate a progressive increase in both parcel count and value at risk as sea levels rise.

It is important to note that much of the land within the SLR hazard footprint is currently undeveloped or in agricultural use. While this reduces immediate structural exposure, it highlights a key distinction:

SLR impacts are spatially concentrated and mappable, whereas agricultural impacts occur across the entire valley floor and upland growing regions, driven by temperature, water availability, and soil conditions rather than inundation.

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Agricultural properties outside the SLR footprint may still experience significant climate-related impacts, including heat stress, water scarcity, and erosion, which are not captured in SLR exposure mapping.

Table 3-65: Napa County Parcel Exposure to Sea Level Rise Total Parcels Total Market
Value ($)
Total Content
Value ($) Total Value ($)
Unincorporated County 13,668 $11,215,199,644 $9,248,691,039 $20,463,890,683 Sea Level Rise Parcel Count % of Total Market Value
Exposure ($)
Content Value
Exposure ($) Total Exposure ($) % of Total
0ft - MHW 112 0.8% $70,888,727 $35,706,164 $106,594,891 0.5% 1ft 113 0.8% $71,680,502 $36,102,051 $107,782,553 0.5%
2ft 121 0.9% $75,658,928 $38,091,265 $113,750,193 0.6%
3ft 133 1.0% $82,614,266 $41,839,340 $124,453,605 0.6%
4ft 136 1.0% $84,423,916 $42,744,165 $127,168,080 0.6%
5ft 146 1.1% $87,207,245 $44,135,832 $131,343,077 0.6%
6ft 155 1.1% $91,134,673 $46,818,012 $137,952,685 0.7%

3.3.9.9.3 Critical Facilities & Infrastructure
Critical facilities and infrastructure exposure to sea level rise is also spatially defined and quantifiable. As summarized in Table 3-66 (Critical Facility Exposure), a limited number of essential facilities, transportation assets, and hazardous material sites fall within the SLR hazard area, with exposure increasing under higher rise scenarios.

Additionally, lifeline infrastructure, including levees, pipelines, rail, and roadway networks, shows increasing exposure as sea levels rise, with total affected infrastructure expanding from approximately 34.7 miles at current conditions to over 120 miles under a 6-foot scenario. See Table 3-67.

The exposure maps illustrate that infrastructure vulnerability is concentrated in southern and tidally influenced areas, where flooding, groundwater rise, and backwater effects may disrupt operations.

In contrast, agricultural infrastructure (e.g., irrigation systems, vineyards, rural roads) is vulnerable to climate change across a much broader area. These impacts are driven by heat, drought, and extreme weather, rather than a single mapped hazard footprint, and therefore require different assessment and mitigation approaches.

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Table 3-66: Napa County Critical Facility Exposure to Sea Level Rise Critical Infrastructure - Sea Level Rise
Infrastructure Type 0ft - MHW 1ft 2ft 3ft 4ft 5ft 6ft
Essential Facilities 1 1 1 1 1 1 2

EOC - - - - - - -
Fire Station 1 1 1 1 1 1 1
Hospital - - - - - - -
Law Enforcement - - - - - - 1
High Potential Loss 1 1 1 1 1 3 3
Adult Residential Care - - - - - - -
Child Care Center - - - - - - -
Church - - - - - - -
Communication Tower - - - - - - -
Dam - - - - - - -
Emergency Shelter - - - - - - -
Farm Worker Housing - - - - - - -
Historic Building - - - - - - -
Library - - - - - - -
Mobile Home Park - - - - - - -
Res Elder Care Facility - - - - - - -
Private School - - - - - - -
Public School - - - - - - -
Real Property Asset 1 1 1 1 1 3 3
Transportation and Lifeline 1 1 1 1 2 3 3
Airport - - - - - - -
Bridge 1 1 1 1 1 1 1
Bus Stop - - - - - - -
HMMWC Asset - - - - - - -
HMMWC Dam - - - - - - -
HMMWC Hydrant - - - - - - -
NG Station - - - - - - -
Power Plant - - - - 1 2 2
Substation - - - - - - -
Wastewater Treatment Facility - - - - - - -
Water Supply Intake - - - - - - -
Water Tank - - - - - - -
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Critical Infrastructure - Sea Level Rise
Infrastructure Type 0ft - MHW 1ft 2ft 3ft 4ft 5ft 6ft
Water Treatment Facility - - - - - - -
Hazmat 1 1 2 5 5 5 5
Geotracker CleanupSite - - - - - - -
HWTS Active Facility 1 1 2 5 5 5 5
Landfill - - - - - - -
Grand Total 4 4 5 8 9 12 13
*Real Property Assets are digitized insurance rolls for demonstrating value and ownership and may have overlapping points with other categories such as fire stations and law enforcement. -Sea Level Rise Risk is cumulative
Table 3-67: Napa County Lifeline Infrastructure Exposure to Sea Level Rise Lifelines (miles) - Sea Level Rise
Infrastructure Type (Linear) 0ft 1ft 2ft 3ft 4ft 5ft 6ft Levee 30.0 44.9 70.8 80.2 86.2 91.5 93.8
NG Pipeline 0.2 0.3 0.4 1.1 1.3 1.5 1.7
Railroad 0.8 1.0 1.8 2.7 3.5 4.2 4.8
Transmission Line 1.9 2.8 2.9 4.4 4.5 4.6 4.7
Street OSM 1.9 2.5 4.3 7.2 10.0 13.4 16.6
Highway & Interstate - - - - - - -
Major Road 0.2 0.3 0.5 0.5 0.7 1.1 1.2
Residential Road 1.6 1.8 2.1 2.5 2.8 2.9 3.2
Road - Secondary - - - - - - -
Road -Tertiary - - - - - - 0.0
Service Road 0.1 0.3 1.3 3.3 5.3 7.9 10.5
Unclassified 0.0 0.1 0.4 0.9 1.2 1.4 1.6
Grand Total 34.7 51.5 80.2 95.6 105.5 115.2 121.7
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DevelopmentTrends
Napa County’s development patterns and policy framework reflect a strong commitment to reducing climate-related risks and supporting long-term resilience. Through a combination of land use regulations, sustainability programs, and regional partnerships, the county has established a foundation for addressing current climate hazards such as extreme heat, drought, wildfire, and flooding. However, as climate conditions continue to change, these hazards are expected to increase in frequency and severity, placing additional pressure on existing systems and development patterns.

Growth in Napa County remains largely guided by policies that emphasize agricultural preservation, urbancentered development, and protection of watershed and open space lands. These development constraints help limit exposure to certain hazards, such as wildfire in undeveloped areas and flooding in sensitive areas, while also preserving natural systems that provide climate resilience benefits, including groundwater recharge and temperature regulation.

The county continues to support a range of programs and initiatives that promote sustainable development and climate adaptation. Efforts such as Sustainable Napa County, the Napa Green Certification Program, and implementation of the California Green Building Standards Code (CALGreen) encourage reduced energy use, improved water efficiency, and environmentally responsible building and agricultural practices.

Participation in regional energy programs, including Marin Clean Energy (MCE), further supports the transition toward renewable energy and reduced greenhouse gas emissions.

These efforts are being advanced through the development of the Regional Climate Action and Adaptation Plan (RCAAP), which expands the County’s approach from emissions reduction to a more comprehensive strategy that integrates climate adaptation, hazard mitigation, and resilience planning. The RCAAP identifies the need to scale up existing programs and incorporate climate considerations more consistently into land use planning, infrastructure investment, and development review processes.

Despite these efforts, continued development, particularly in rural, hillside, and agricultural areas, may increase exposure to climate-related hazards if not carefully managed. Future development will need to account for changing hazard conditions, including increased wildfire risk, water supply constraints, and extreme heat, as well as the cumulative impacts of multiple hazards over time.

In addition, climate change is expected to influence agricultural practices and pest dynamics, requiring ongoing coordination between the County, agricultural producers, and regulatory agencies. Existing programs, such as the Winegrape Pest and Disease Control District, will continue to play an important role in monitoring and managing pest risks, while adaptation strategies may include improved data collection, integrated pest management, and enhanced information sharing to support agricultural resilience.

Overall, Napa County’s development trends are generally aligned with climate resilience goals; however, expanded implementation, continued coordination, and integration of climate projections into planning decisions will be necessary to effectively address future climate-related risks.

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Climate Change Hazard Problem Statements
As part of the mitigation action identification process, the Napa County Planning Team developed areas of concern (i.e., problem statements) that summarize the county’s most pressing climate change-related vulnerabilities and challenges. The problem statements were developed based on the updated risk assessment and vulnerability analysis contained herein, as well as the team’s local knowledge and experience and community input. The problem statements address a broad spectrum of concerns, from direct impacts on residents and vulnerable populations to threats to critical infrastructure and long-term recovery.

These problem statements are not intended to be all-encompassing or to describe each and every issue associated with climate change. Instead, they highlight the most urgent concerns that can be addressed within the scope of this MJHMP. Each statement will be linked to at least one mitigation action, ensuring that identified needs are met with specific, measurable, and equitable solutions. Table 3-68 presents the climate change problem statements for Napa County, along with their associated areas of concern and reference numbers for cross-linking to the mitigation actions in Table 4-4.

Table 3-68: Napa County Climate Change Hazard Problem Statements Problem No. Hazard Area of
Concern
Primary
Agency
Problem Description Related MA
ps-AG-NCo-0 Climate
Change
Impact Napa County Climate change is altering the growing season, causing bud break sooner and leaving new
vine growth vulnerable to frost for extended
periods, and intensifying pest and pathogen
risks by shifting species composition,
expanding breeding seasons, and accelerating
disease transmission.
ma-CC-NCo-17,
ma-AG-NCo-1,
ma-AG-NCo-2
ps-AG-NCo-1 Climate
Change
Victim Napa County The agricultural industry in Napa County is a main driver of the local economy, and
agricultural impacts from climate change and
other natural disasters could adversely affect
the entire community but especially food and
wine industry workers.
ma-CC-NCo-17,
ma-AG-NCo-2,
ma-AG-NCo-1,
ma-CC-NCo-18
ps-CC-NCo-4 Climate
Change
Threat Napa County Napa County’s capital improvement programs for critical facilities and infrastructure do not
consistently incorporate projections for future
sea-level rise, tidal flooding, or associated
climate-driven shoreline hazards, potentially
leaving assets in low-lying areas vulnerable to
associated impacts.
ma-CC-NCo-13,
ma-CC-NCo-14,
ma-DR-NCo-26,
ma-FL-NCo-51,
ma-FL-NCo-54,
ma-FL-NCo-57
ps-CC-NCo-7 Climate
Change
Threat Napa County The confluence of climate change-driven sealevel rise, atmospheric river and heavy rain events, and King Tides poses risks to areas
along the Napa River, including industrial uses,
wineries, and parts of Downtown Napa.
ma-CC-NCo-13,
ma-CC-NCo-14,
ma-AG-NCo-1,
ma-FL-NCo-54,
ma-FL-NCo-57
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Section 4.Mitigation Strategy
This section describes the mitigation strategies developed for the 2026 MJHMP to reduce or eliminate the long-term risks of high-priority hazards impacting Napa County. Building upon the findings of the risk assessment detailed in 0, the strategies in this plan outline prioritized mitigation actions, projects, and policies aimed at safeguarding vulnerable populations, protecting property and critical infrastructure, and enhancing overall community resilience.

4.1 Mitigation Goals
Hazard mitigation plans must define clear goals for reducing long-term vulnerabilities to natural hazards.

For this plan, the county-wide Hazard Mitigation Planning Team established goals using findings from the risk assessment, input from the planning team, and feedback from the public gathered through surveys, stakeholder interviews, and document review. The four goals, developed by the Planning Team and confirmed by jurisdictional teams, outline broad priorities for protecting people, property, services, infrastructure, and the environment. These goals provide the framework for the 2026 Napa County Mitigation Strategy. The mitigation actions that follow are specific and measurable steps designed to achieve these goals through both jurisdiction-specific initiatives and a coordinated county-wide approach.

Goal 1: Protect people from loss of life, injury,
and economic damage from hazards.

Goal 2: Protect critical facilities, infrastructure,
property, and the continuity of essential services
from hazards.

Goal 3: Preserve natural resources and ecological
functions as hazard mitigation.

Goal 4: Promote community resilience through planning,
policies, capital improvements, education, and interjurisdictional collaboration.

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4.2 Capabilities & Opportunities
This section provides a detailed assessment of the current capabilities of Napa County to support hazard mitigation, as well as future opportunities and funding options. This consists of describing how the county is planning for hazards and growth and a summary of its existing capabilities and the potential for enhancement. A summary of funding opportunities to advance the goals of this MJHMP is also provided in this section, including state and federal mechanisms and ways the participating jurisdictions can leverage their shared resources to fund coordinated mitigation efforts.

Volume 2 of this MJHMP describes the planning efforts, existing capabilities, and future opportunities for each of the other participating jurisdictions as part of their annexes. Additional details about the regulatory environment surrounding each hazard are found in the hazard profiles in Section 3.3.

4.2.1 Planning for Hazards & Growth
Napa County and the incorporated municipalities each maintain general plans that serve as the foundation for guiding land use, development, and long-term community priorities. Napa County is a general law county, which means it establishes and enforces its own development regulations in compliance with the State of California’s stringent planning, zoning, subdivision, building, and environmental standards. This framework ensures that future development in the unincorporated areas is carefully managed, with a strong emphasis on recognizing and mitigating the impacts of natural hazards.

For example, the Napa County Flood Control and Water Conservation District continues to implement its Napa River Flood Management Plan to protect existing development from flood impacts and reduce or mitigate impacts from new development in floodplains. Napa County and the Cities of American Canyon, Napa, St. Helena, and Calistoga and the Town of Yountville collectively administer the Napa County Stormwater Pollution Prevention Program. The communities in the Napa County Operational Area have all adopted Seismic Retrofit ordinances to reinforce all historic buildings. And all municipalities in the county have adopted similar building and fire codes to streamline permitting and enforcement and ensure consistent protective standards for new development.

The county’s General Plan, alongside the general plans of participating municipalities such as the City of Napa and Town of Yountville, provide comprehensive planning frameworks that integrate hazard mitigation strategies into land use decisions, community safety, and infrastructure investments. These plans address long-term issues such as sustainable growth, climate change resilience, and protection of vulnerable populations.

Incorporating hazard analysis into general plans and development regulations enables both the county and its municipalities to meet state requirements while reducing risks from natural hazards such as wildfire, flooding, drought, and extreme heat. Climate change is increasing the frequency and severity of these hazards, underscoring the importance of proactive planning and durable mitigation strategies.

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Through coordinated planning, adherence to strict environmental regulations, and investment in resilience measures, the county and municipalities are working to foster sustainable, safe, and adaptable communities. Together, these efforts provide a consistent and comprehensive approach to balancing growth with hazard risk reduction and climate adaptation across the region.

Long-Range Planning & Growth Management
Anticipating future growth in Napa County requires a proactive approach that balances state housing mandates with local hazard mitigation priorities. Growth management has long been a defining feature of the county’s planning framework. Since 1968, an Agricultural Preserve has been established in Napa County, concentrating growth within incorporated municipalities and established unincorporated communities while limiting sprawl into rural and hazard-prone areas. Agricultural and rural preservation goals were further implemented by the adoptions of Measure A (Growth Management System) in 1980 and Measure J in 1991, significantly limiting the conversion of designated agricultural lands for non-agricultural uses. This framework, combined with California’s stringent planning, zoning, subdivision, building, and environmental standards, helps ensure that future development occurs in areas with appropriate infrastructure and lower hazard exposure.

At the same time, all municipalities in Napa County are subject to the State’s Regional Housing Needs Allocation (RHNA), which requires each to plan for a fair share of new housing across all income levels.

Accommodating RHNA targets in a county constrained by agricultural preservation, steep topography, and hazard-prone landscapes creates both opportunities and challenges. Most new housing will need to be located within existing urban centers such as Napa, American Canyon, St. Helena, Yountville, and nearby unincorporated communities, where infrastructure is already in place. Concentrating growth in these areas helps to preserve rural lands and environmentally sensitive habitats, but also underscores the importance of investing in resilient infrastructure and retrofitting older housing stock that remains vulnerable to natural hazards.

The Napa County General Plan, last updated in 2023, serves as the overarching blueprint for managing this growth while addressing hazard resilience. Its Safety Element establishes policies for natural hazards including flood, wildfire, and earthquake hazards, and is being further updated to integrate this MJHMP.

Other General Plan elements, such as the Agricultural Preservation and Land Use Element, direct land use and housing decisions in a way that complements hazard mitigation goals. Together, these planning frameworks ensure that decisions about future development are informed by the most current hazard data and mitigation strategies.

By aligning growth management tools such as Measures A and J, the General Plan, and RHNA compliance with hazard mitigation priorities, Napa County and the incorporated municipalities are working to achieve two critical goals: meeting the region’s pressing housing needs and reducing long-term risk to people, property, and natural systems. As one more step toward reducing hazard risk, the County and municipalities will adopt this MJHMP by reference into their general plans pursuant to AB 2140, ensuring stronger integration between hazard mitigation and long-range land use planning.

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Building Codes & Development Standards
Napa County’s development strategies integrate comprehensive planning frameworks and regulatory measures to guide growth while minimizing risks from natural hazards. Nationally, building codes have continually improved disaster resilience and, since 1990, those great improvements have added approximately one percent to construction costs. (National Institute of Building Sciences, 2019) In addition, California’s building codes are considered some of the world’s most robust and set minimum standards to safeguard against many of the natural hazards that affect communities within the state. These codes form a strong foundation for safe construction practices which the county and municipalities enforce.

The county is required to regularly update its building and development codes to meet the minimum standards required by California, including the CBC which was last updated in 2025. California’s minimum code requirements provide some of the safest construction standards in the world and are meant to reduce risk to occupants from high wind, seismic activity, landslides, flood, wildfire, and other natural hazards.

Further, climate change impacts are also required to be addressed through the adoption and regular updating of California’s Green Building Standards and Energy Codes.

For flood hazards, specifically, Napa County participates in the National Flood Insurance Program (NFIP) and Community Rating System (CRS), in addition to adhering to other California minimum floodplain development standards. All development within designated flood hazard areas must meet minimum flood protection standards as set forth by FEMA; however, the county has adopted higher standards than the NFIP minimums, including a requirement to elevate or floodproof the lowest floor of structures at least one foot above the base flood elevation, known as a “freeboard.” A freeboard is a factor of safety for purposes of floodplain management to compensate for the many unknown factors that could contribute to flood heights or elevations greater than what is anticipated on regulatory flood maps, such as bridge openings, climate change, sea level rise, and the hydrological effect of watershed urbanization.

The Napa County Code incorporates stringent building and development regulations to mitigate hazards for both new and existing structures, and many chapters of the code recognize the diverse terrain found throughout the county by differentiating between valley, mountain, and other areas where hazard risks and impacts may vary greatly. These code sections include:
▪ 2025 California Building, Mechanical, Plumbing, Electrical, Existing Building, Residential, Green Building Standards, Energy, and Historical Building Codes (Title 15) ▪ Wildland-Urban Interface and Fire Codes (Chapters 15.13 and 15.32), including construction and design, defensible space, vegetation management, and emergency access requirements in compliance with the 2025 California Fire Code
▪ Environment Regulations (Title 16), including requirements for specific hazardous uses and areas and for stormwater management
▪ Floodplain Management Regulations (Chapter 16.04), in compliance with NFIP requirements and including higher standards such as a one-foot freeboard CAL OES SUBMITTAL - JUNE 2026
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▪ Zoning Ordinance (Title 18), including agricultural, timber, and watershed preservation zones and development standards; slope grading, erosion control, water quality, and landscape preservation requirements; water conservation regulations for landscaping and groundwater; and other standards related to General Plan conformity and public safety
▪ Subdivision Ordinance (Title 17), including General Plan conformity requirements and design standards that prohibit subdivision in wildfire, flood, geologic, or other hazard areas without adequate mitigation
These regulations are designed to protect public health, safety, and welfare, and to limit the impacts of natural disasters on development. In the county’s hazard-prone areas, new development is limited and, where development is feasible and permitted, these codes emphasize minimizing exposure and vulnerability to hazard risks through appropriate siting, advanced construction techniques, maintaining adequate access for emergency services, and other mitigation methods.

Environmental Regulations
Napa County anticipates and plans for its future growth while maintaining a robust regulatory framework to mitigate exposure and vulnerability to hazards. Further, the State of California has some of the most rigorous environmental regulations in the nation to which the county, municipalities, and all new development within them are bound.

California Environmental Quality Act (CEQA)
Under the California Environmental Quality Act (CEQA), the county’s General Plan and any specific plans that propose land use changes or significant development projects must include extensive evaluations of hazards and potential impacts. CEQA analysis requires consideration of factors such as proximity to floodplains, wildfire-prone areas, or seismic zones. Additionally, mitigation measures proposed in CEQA documents aim to reduce environmental and hazard-related risks, including updates to infrastructure, evacuation planning, or restrictions on development in high-risk areas.

For example, if a specific plan proposes rezoning to allow residential development in a previously undeveloped area near the wildland-urban interface (WUI), CEQA would necessitate an assessment of wildfire risk to the development. The resulting analysis might recommend increased setbacks, advanced fire-resistant construction materials, and enhanced emergency access to mitigate identified hazards.

CEQA also requires analysis and mitigation of environmental impacts related to climate change. As part of the review process, for example, the proposed development’s contributions to greenhouse gas (GHG) emissions must be evaluated and mitigation techniques or other alterations to the project may be required to reduce future emissions that could result from the project.

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California Climate Change Legislation
In California, counties and municipalities are required to address climate change through various state laws and policies designed to promote sustainability, reduce GHG emissions, and increase resilience to climaterelated hazards. In addition to applicable CEQA requirements and the county’s adopted sustainability standards outlined in Section 4.2.1.2, key senate bills (SB), assembly bills (AB), executive orders (EO), and other state environmental legislation includes:
▪ SB 375 – Sustainable Communities and Climate Protection Act: Requires jurisdictions to integrate regional transportation planning and land use to reduce GHG emissions, particularly by fostering development near transit hubs and reducing vehicle miles traveled. ▪ AB 32 and SB 32 – Global Warming Solutions Act and Amendments: Mandates that jurisdictions contribute to California's broader goals of reducing GHG emissions to 40% below 1990 levels by 2030 and achieving carbon neutrality by 2045.
▪ SB 379 – General Plan Safety Element: Requires jurisdictions to incorporate climate adaptation and resilience strategies into the safety element of their general plan to address risks such as wildfires, extreme heat, drought, and sea-level rise.
▪ SB 1000 – General Plan Environmental Justice Element: Mandates the inclusion of an environmental justice element in general plans for communities which have been (or are anticipated to be) disproportionately impacted by environmental hazards, often compounded by climate change. ▪ Title 24 – California Building Code (CBC): Establishes energy efficiency and renewable energy requirements to reduce GHG emissions from the built environment, which jurisdictions enforce through local permitting processes.
▪ EO B-30-15 and EO N-79-20: Establish statewide targets for climate resilience and decarbonization of transportation and energy sectors, influencing local and regional planning efforts.

Napa County incorporates these state mandates into its local planning, leveraging the General Plan and hazard mitigation strategies to prepare for the increasing risks of wildfires, drought, flooding, coastal hazards, severe weather, and extreme heat caused and compounded by climate change. By aligning with state goals, the county ensures its development contributes to a sustainable and resilient future for its communities.

4.2.2 Napa County Capabilities & Opportunities Assessment To develop a realistic and actionable mitigation strategy, it must account for existing jurisdictional capabilities and what future opportunities there are to enhance those capabilities for purposes of hazard mitigation. This section provides an assessment of Napa County’s existing capabilities and future opportunities. This assessment also identifies opportunities to integrate this MJHMP into future planning, policies, or programs to weave mitigation efforts into daily operations and address hazard problems wholistically. Capabilities are categorized into four groups and include various mechanisms.

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▪ Planning and Regulatory Capabilities: Existing long-range plans, emergency response plans, hazardspecific plans, land use policies, and building and development standards. ▪ Administrative and Technical Capabilities: Available expertise in emergency services, engineering, grant management, and community planning.
▪ Fiscal Capabilities: Budgetary capacity, taxing authority, grants, and other funding mechanisms that can support mitigation projects.
▪ Outreach and Education Capabilities: Existing programs for providing technical assistance, community education, public warnings, and stakeholder engagement.

A full description of the process used to develop the capabilities and opportunities assessments is provided in Section 2.3.3. The capabilities and opportunities assessments for other participating jurisdictions are found in the Volume 2 annexes of this plan.

Expanding & Improving Existing Capabilities
The capabilities assessment exercise presents an opportunity for Napa County and the other participating jurisdictions to examine what capabilities they do and do not currently have and where it makes the most sense to expand and improve upon those capabilities in the future. These assessments shaped mitigation actions for hazards generally and specifically that focus on expanding and improving existing planning mechanisms, policies, and programs. The expansions and improvements were based upon identified vulnerabilities and areas of concern specific to each jurisdiction, as profiled in Volume 1, Section 3.3, and each jurisdiction’s annex in Volume 2.

The three “HMP Integration” columns that identify the capability’s status and usage are color-coded with green, yellow, or orange shading to communicate the following:
▪ Status: If the capability is present at all and what level of use it has generally. ▪ Current Mitigation Use: If the capability is currently being used in mitigation efforts, specifically, and at what level.
▪ Future Opportunity: If there is a future opportunity to integrate the capability into mitigation efforts and at what level.

Napa County Capabilities & Opportunities Summary
This Capabilities and Opportunities Assessment for Napa County summarizes the various types of capabilities it has for hazard mitigation currently. The assessment also identifies opportunities to integrate, expand, and improve the county’s capabilities for future hazard mitigation. Table 4-1 provides a comprehensive list of capabilities and identifies the current status, current mitigation use, and future opportunities.

Planning & Regulatory
Napa County demonstrates strong planning and regulatory capabilities, with most planning mechanisms currently in use and widely applied to hazard mitigation. The County has adopted the 2025 California CAL OES SUBMITTAL - JUNE 2026
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Building Standards Code, maintains hazard-related development standards, and enforces zoning, floodplain, stormwater, and fire regulations that directly reduce risk. Long-range planning documents such as the General Plan, Community Wildfire Protection Plan, Emergency Operations Plan, Climate Action and Adaptation planning, and the Capital Improvement Program are all actively used to support mitigation.

Key opportunities for future hazard mitigation plan integration are to more explicitly link mitigation actions to implementation mechanisms already embedded in the Capital Improvement Program, Climate Action Plan, CWPP, and building and development codes, ensuring that mitigation priorities directly inform capital investments, long-range planning decisions, and regulatory updates (e.g., ma-EQ-NC-XX, ma-FL-NC-XX, and ma-DR-NC-XX). This MJHMP prescribes multiple mitigation actions that further integrate hazard mitigation, including results of the updated vulnerability assessment, into these existing mechanisms.

Administrative & Technical
The county’s administrative and technical capacities are also strong, with existing personnel, departments, and systems in place to support mitigation planning and implementation. Planning, engineering, building, floodplain management, emergency management, GIS, and public works staff are all available and actively involved in mitigation-related work. ALERT Napa County, WEA, and IPAWS provide robust multi-hazard warning capability. An opportunity for enhanced integration lies in formalizing the use of hazard mitigation data—such as risk assessments, damage histories, and equity considerations—across departments, particularly by adopting prioritization frameworks for resource allocation and increasing interagency coordination. The integration of updated hazard mapping informed by climate change is also a priority in this plan.

Fiscal
The county’s fiscal capabilities are moderate, with several funding tools already in use but not always applied specifically to hazard mitigation. The County uses development fees, stormwater fees, capital improvement funding, and CDBG funds, among other mechanisms. Bonding, special taxes, and benefit assessments are available but used selectively and rarely to support mitigation. Key integration opportunities include aligning the Capital Improvement Program with mitigation priorities and expanding the use of CDBG, special districts, and bond financing for resilience projects, particularly for flood, wildfire, and infrastructure protection.

Education & Outreach
The county’s education and outreach capabilities are generally strong, including tools such as Ready Napa County, social media, CERT, Firewise communities, Fire Safe Councils, public safety events, and technical assistance. These programs provide a foundation for community preparedness and mitigation awareness.

Some outreach tools could still be expanded, such as public education through more formalized campaigns, additional printed resources, or participation in national preparedness programs.

A key opportunity for integration is linking hazard mitigation initiatives with county outreach, Firewise and Fire Safe Council programs, and climate adaptation education, which would improve public understanding of risk reduction actions and increase participation in mitigation efforts. A major county-wide priority in CAL OES SUBMITTAL - JUNE 2026
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this plan is to collaborate with the other participating jurisdictions to create a coordinated public outreach and education strategy through consistent, aligned messaging. This effort will leverage partnerships with trusted voices and existing social networks to reach diverse communities with out-of-the-box resources and tools that are highly inclusive and accessible.

ASSESSMENT LEGEND
HMP Integration
Status Current Mitigation Use Future Opportunity
Currently in use or present. Used widely for mitigation. Opportunity to expand and integrate. (Sort of) Seldomly used or limited
presence.

Limited use in mitigation planning.

Limited opportunity to expand and
integrate.
(No) Not present or available. Not used in mitigation planning. No opportunity to expand or integrate.

Table 4-1: Napa County Capabilities and Opportunities Assessment HMP Integration
Resource Status
Current
Mitigation
Use
Future
Opportunity Notes / Additional Detail
Planning and Regulatory
Capabilities
Construction and Future
Development Regulations
Building Codes
Green Green Yellow
2025 California Building Standards Code (Title 24)
adopted; County also adopts 2025 CA codes by
ordinance (e.g., Existing Building Code; Mechanical;
Fire Code)
BCEGS Rating Green Green Yellow Rating of 3
Public Protection (ISO Class) Green Green Yellow Class 6 Hazard-Related Development
Standards
Green Green Yellow
Water Conservation for Landscape Design (Ch.

18.118); Groundwater Conservation (Ch. 17.59) Fire
Code (Ch. 15.32); Fire Zone Regulations (Ch. 8.32);
Floodplain Ordinance (Ch. 16.04); Stormwater Mgmt
(Ch. 16.28)
Zoning Ordinance
Green Green Yellow
Title 18, including Agricultural Preserve and
Watershed Districts (Ch. 18.16 and 18.20) protect
agriculture, watersheds and floodplain tributaries
from fire, pollution and erosion; Conservation
Regulations (Ch. 18.108) protect from excessive soil
loss and water quality/ quantity issues;
Groundwater Conservation (Ch. 18.141); Water
Conservation for Landscape Design (Ch. 18.118)
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HMP Integration
Resource Status
Current
Mitigation
Use
Future
Opportunity Notes / Additional Detail
Planning and Regulatory
Capabilities
Hazard-Specific Ordinance
Green Green Yellow
Groundwater Conservation (Ch. 17.59); Fire Code
(Ch. 15.32); Fire Zone Regulations (Ch. 8.32);
Floodplain Ordinance (Ch. 16.04); Stormwater Mgmt
(Ch. 16.28); Western Grapeleaf Skeletonizer Control
Regulation (Ch. 8.40)
Growth Management Ordinance
Green Green Yellow
Growth Management System part of GP (Ag.

Preservation and Land Use Elements); Implemented
by Housing Allocation Program in County Code (Ch.

8.02)
Hazard Reduction Programs
(Annually Conducted)
Capital Improvements Program
(CIP) or Plan Green Green Yellow CIP 5-year program
General Plan
Erosion/Sediment Control
Program Green Green Yellow Ch 16 and 18 of Code of Ordinances Erosion Control Plan
Hazard-Related Public Outreach
Program Green Green Yellow See Education and Outreach Capabilities Urban Water Management Plan Green Green Yellow Groundwater Conservation (Ch. 17.59); Groundwater Sustainability Plan
Stormwater Management
Program (Annual Inspections) Green Green Yellow Stormwater Mgmt (Ch. 16.28); Groundwater Sustainability Plan
Seismic Safety Program (Nonstructural) Green Green Green Through Ready Napa County program Earthquake Modernization Plan
(Building Safety) Green Green Yellow 2022 California Building Standards Code (Title 24) adopted, including statewide seismic standards
Hazard Plans
General Plan Safety Element Green Green Green General Plan updated 2013 Site Plan Review Requirements Green Green Yellow Titles 16 & 18 General Plan Environmental
Justice Element Yellow Yellow Yellow No standalone EJ element but addressed in Housing and other elements
Community Wildfire Protection
Plan (CWPP) Green Green Yellow Countywide CWPP adopted May 2021; to be updated 2026
Economic Development Plan Green Green Yellow Adopted element of the General Plan; 2019–2022 Strategic Plan
Floodplain Management Plan Green Green Yellow Floodplain Ordinance (Ch. 16.04) Stormwater Management Plan
Green Green Yellow
Stormwater Mgmt (Ch. 16.28); Napa Countywide
Stormwater Pollution Prevention Program;
Groundwater Sustainability Plan
Emergency Operations Plan Green Green Yellow EOP updated 2024 Climate Action Plan Green Green Yellow Regional Climate Action & Adaptation Plan (RCAAP) updated 2025-2026
Climate Vulnerability
Assessment Green Green Yellow Part of RCAAP updated 2025-2026 CAL OES SUBMITTAL - JUNE 2026
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HMP Integration
Resource Status
Current
Mitigation
Use
Future
Opportunity Notes / Additional Detail
Planning and Regulatory
Capabilities
Urban Greening Plan Yellow Yellow Green Addressed in RCAAP updated 2025-2026 Ground Water Management
Planning / Plans Green Green Yellow Stormwater Mgmt (Ch. 16.28); Groundwater Sustainability Plan
National Flood Protection
Program (NFIP)
Floodplain Management
Regulations Green Green Yellow Floodplain Ordinance (Ch. 16.04) exceeds minimum NFIP standards
Flood Insurance Education and
Technical Assist. Green Green Green Provided via County website (FAQs, insurance info, staff contacts)
Flood Insurance Study Green Green Green FEMA FIS adopted 2016 Elevation Certificates
Green Green Yellow
Reviewed and kept by Engineering Division of
Planning, Building & Environmental Services
(PBES) Department
Flood Hazard Mapping / ReMapping Green Green Green FEMA FIRMs adopted 2008-2016 Community Rating System (CRS) Green Green Green Class 7; participating since 2018 Administrative and
Technical
Community Planning and
Development Services
Community Planner Green Green Green PBES Dept, Planning Division staff Planner/Engineer (Land
Development) Green Green Green PBES Dept, Planning and Engineering Divisions staff
Engineer/Professional
(Construction) Green Green Green Public Works Dept staff Planner/Engineer/Scientist
(Natural Hazards) Green Green Green PBES Dept, Planning and Engineering Divisions staff
Transportation Planner Green Green Green Public Works Dept staff Resiliency Planner Green Green Green PBES Dept, Conservation and Natural Resources Divisions staff
Building Code Official (Full time
or Augmented) Green Green Green PBES Dept, Building Division staff Floodplain Administrator Green Green Green PBES Dept Director and staff Fire Marshal Green Green Green Fire Dept staff
Dedicated Public Outreach
Personnel Yellow Yellow Green No dedicated staff; duties performed as needed across all departments
GIS Specialist and Capability Green Green Green PBES Dept GIS staff Emergency Manager Green Green Green Sheriff's Office of Emergency Services (OES) staff Dedicated Grant Manager, Writer,
or Specialist Yellow Yellow Green No dedicated staff; duties performed as needed across all departments
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HMP Integration
Resource Status
Current
Mitigation
Use
Future
Opportunity Notes / Additional Detail
Planning and Regulatory
Capabilities
Other N/A N/A N/A
Warning Systems/Services
General Green Green Green ALERT Napa County, WEA and IPAWS Flood Green Green Green ALERT Napa County, WEA and IPAWS Tornado Green Green Green ALERT Napa County, WEA and IPAWS Wildfire Green Green Green ALERT Napa County, WEA and IPAWS Geological Hazards Green Green Green ALERT Napa County, WEA and IPAWS Fiscal Capabilities
Financial Resources for
Hazard Mitigation
Levy Taxes for Specific Purposes Yellow Yellow Green May levy special taxes with voter approval Utilities Fees N/A N/A N/A Not a utility provider
Benefit assessments Yellow Yellow Green Limited use (e.g., Flood Control and Water Conservation District)
Community Development Block
Grants Yellow Yellow Green Receives CDBG funds for infrastructure and resilience improvements
System Development Fee Green Green Green Imposed on new development for capital needs General Obligation Bonds to
Incur Debt Yellow Yellow Green Used selectively due to debt limits and voter threshold
Special Tax Bonds to Incur Debt
Yellow Yellow Green
Rarely used directly; future opportunity in
partnership with special districts for mitigation
projects
Withheld Spending in HazardProne Areas Yellow Yellow Green No formal policy; future opportunity Stormwater Service Fees Green Green Green Imposed on new development Capital Improvement Project
Funding Green Green Green 5-year CIP funds
Education / Outreach
Capabilities
Education/Outreach
Resources
Website Dedicated to Hazard
Topics Green Green Green Ready Napa County
Dedicated Social Media Green Green Green County and OES social media (Facebook, Instagram, YouTube, etc.)
Local Citizen Groups That
Communicate Hazard Risks Green Green Green Firewise, CERT Hazard Info. Avail. at Library/
Planning Desk Green Green Green PBES Dept and OES websites and staff CAL OES SUBMITTAL - JUNE 2026
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HMP Integration
Resource Status
Current
Mitigation
Use
Future
Opportunity Notes / Additional Detail
Planning and Regulatory
Capabilities
Annual Public Safety Events Green Green Green Hosted by Fire Dept and OES Ability to Field Public Tech.

Assistance Requests Green Green Green OES and PBES, Fire, and Public Works Depts Public Safety Newsletters or
Printed Outreach Yellow Yellow Green Printed materials limited, but online resources widely available
Community Emergency
Response Team (CERT) Green Green Green Active CERT and regular training Fire Safe Councils Green Green Green Napa Communities Firesafe Foundation consists of 23 FSCs
Firewise Green Green Green 18 Firewise communities
StormReady Orange Orange Green Not designated; future opportunity Resource Conservation Districts Green Green Green Napa County RCD Other N/A N/A N/A

4.2.3 Funding Opportunities
The federal, state, and local funding opportunities listed in Table 4-2 are provided as potential options to leverage and increase the capabilities and adaptive capacities of Napa County and the other participating jurisdictions. This includes the FEMA Hazard Mitigation Assistance (HMA) grant program as well as other national and state programs and grants. Note that this list serves as a resource and is not exclusive or exhaustive.

Table 4-2: Federal, State, and Local Funding Opportunities Agency /
Program Name Potential Programs / Grants
Federal Funding Opportunities
FEMA HMA and Other
Programs
FEMA HMA grant programs include:
▪ Hazard Mitigation Grant Program (HMGP): fema.gov/hazard-mitigation-grantprogram ▪ Building Resilient Infrastructure and Communities (BRIC)* Program:
fema.gov/grants/mitigation/building-resilient-infrastructure-communities ▪ Flood Mitigation Assistance (FMA) Program: fema.gov/flood-mitigationassistance-grant-program For more information on current HMA grants visit fema.gov/hazard-mitigationassistance CAL OES SUBMITTAL - JUNE 2026
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Agency /
Program Name Potential Programs / Grants
Assistance to Firefighters Grant (AFG) Program: Grants for firefighting resources, fire prevention and safety, and staffing for adequate response. fema.gov/welcomeassistance-firefighters-grant-program Fire Prevention and Safety (FP&S) Program: Grants to enhance the safety of the public and firefighters and administered as part of the AFG Program. FP&S Grants are offered to support projects that cover fire prevention and safety activities and research and development activities. fema.gov/fire-prevention-safety-grants Emergency Management Performance Grants (EMPG): Grants for equipment such as backup generators. fema.gov/emergency-management-performance-grant-program Regional Catastrophic Preparedness Grant Program (RCPGP): Grants for housing, logistics, and supply chain management encouraging innovative regional solutions to issues related to catastrophic incidents. fema.gov/regional-catastrophic-preparednessgrant-program The Flood Mitigation Assistance Swift Current (Swift Current) effort provides funding to mitigate buildings insured through the NFIP after a major disaster declaration following a flood-related disaster event to reduce risk against future flood damage. fema.gov/grants/mitigation/learn/flood-mitigation-assistance/swift-current Office of State and
Community Energy
Programs (SCEP)
The Office of State and Community Energy Programs (SCEP) is part of a concerted effort at the DOE to extend the capacity and capability of states, tribes, local governments, schools, and community-serving organizations to implement high-impact, selfsustaining clean energy projects that center the needs of low-income and disadvantaged communities. SCEP does this through the management and oversight of over $16 billion in formula grants, competitive grant awards, consumer rebate grants, and technical assistance. energy.gov/scep/office-state-and-community-energy-programs U.S. Department of
Agriculture (USDA)
Programs
USDA offers a variety of programs to help farmers, ranchers, communities, and businesses that have been hard hit by natural disaster events. Available FSA programs; are available at farmers.gov. For additional USDA programs visit: fsa.usda.gov/programsand-services/disaster-assistance-program U.S. Bureau of Reclamation
(BOR) Programs
BOR has annual funding available through the WaterSMART grant program, including for Water Reclamation and Reuse, Drought Resiliency Project, and Water and Energy Efficiency Grant. usbr.gov/watersmart/
State Funding Opportunities
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Agency /
Program Name Potential Programs / Grants
California Department of
Housing and Community
Development (HCD)
Programs
Community Development Block Grants (CDBG) include:
▪ Community Development (CD)
▪ Economic Development (ED)
▪ Neighborhood Stabilization Program (NSP)
▪ Disaster Recovery Initiative (DRI)
▪ Emergency Solutions Grant (ESG) Program: Funds projects that serve homeless individuals and families with emergency housing and supportive services or that provide homelessness prevention assistance. The Homeless Emergency Assistance and Rapid Transition to Housing (HEARTH) Act of 2009 places new emphasis on assisting people to quickly regain stability in permanent housing after experiencing a housing crisis or homelessness.

For more information on current grants visit hcd.ca.gov/grants-and-funding California Governor’s Office
of Emergency Services (Cal
OES) Programs
Get notified via email when a new Competitive Funding Opportunity (CFO) or Public Meeting Notice is released: Join the Cal OES Grants Management Mailing List Search for active Cal OES grant programs here: caloes.ca.gov/office-of-thedirector/policy-administration/finance-administration/grants-management/searchfor-grants/ California Department of
Forestry and Fire Protection
(CAL FIRE)
Wildfire Prevention and Forest Health Grants: Supports CWPPs and collaborative wildfire risk reduction. fire.ca.gov/what-we-do/grants
California Water Resources
Control Board Programs
The Division of Financial Assistance (DFA) has the lead in administering the State Water Resources Control Board’s financial assistance programs. These programs include loan and grant funding for construction of drinking water treatment and distribution systems, municipal sewage conveyance and treatment systems; water recycling facilities; remediation for underground storage tank releases and groundwater contamination; technical assistance for small communities; nonpoint source pollution control projects; interim water, and operation and maintenance/Administrator support for small, disadvantaged community water systems; and drought support for individual households. DFA coordinates closely with the Division of Administrative Services, Office of Chief Counsel, Division of Drinking Water, Division of Water Quality, and the Regional Water Quality Control Board, as well as other State, federal, local, and nongovernmental organizational partners. DFA administers the Operator Certification Program, which oversees the certification of all wastewater treatment plant and drinking water treatment plant and distribution system operators in California. For more information visit: waterboards.ca.gov/water_issues/programs/grants_loans/ CAL OES SUBMITTAL - JUNE 2026
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Agency /
Program Name Potential Programs / Grants
California Department of
Transportation (CalTrans)
Programs
Caltrans' Local Assistance Program oversees more than one billion dollars annually available to over 600 cities, counties and regional agencies for the purpose of improving their transportation infrastructure or providing transportation services. This funding comes from various Federal and State programs specifically designed to assist the transportation needs of local agencies. Annually, over 1,200 new projects are authorized through the Local Assistance Program of which approximately 700 are construction projects. dot.ca.gov/programs/local-assistance
California Community
Emergency Response Team
(CERT) Program Manager
Course
There are over 450 CERT programs in California. The State CERT Administrator provides technical support and CERT updates to programs in California. caloes.ca.gov/office-ofthe-director/operations/planning-preparedness-prevention/community-emergencyresponse-team/ California Residential
Mitigation Program
The California Residential Mitigation Program (CRMP): Established to carry out mitigation programs to assist California homeowners who wish to seismically retrofit their houses. californiaresidentialmitigationprogram.com/ ▪ Earthquake Brace + Bolt (EBB) Program: Developed as part of the CRMP to help homeowners lessen the potential for damage to their houses during an earthquake by offering eligible homeowners up to a $3,000 incentive to seismically retrofit their homes. earthquakebracebolt.com/ California Air Resources
Board (CARB) Incentives,
Grants, and Credit Programs
These programs have hundreds of millions of dollars in grants available over the next several years to reduce emissions from on- and off-road vehicles and equipment. arb.ca.gov/ba/fininfo.htm
California Department of
Water Resources (DWR)
Grants and Loans
Agency offers a variety of grants and loans related to integrated regional water management, flood mitigation, water conservation and efficiency, environmental restoration, groundwater, water quality, and water supply. water.ca.gov/Work-WithUs/Grants-And-Loans California Department of
Conservation (DOC)
Funds projects that improve soil, water, and habitat conservation at the local level. conservation.ca.gov/information-for/funding-grants-easements California State Coastal
Conservancy
Provides support for nature-based solutions, shoreline protection, and community resilience. scc.ca.gov/grants/
2024 Climate Bond
(Proposition 4)
Voters passed the 2024 Climate Bond (Proposition 4) in November 2024, a general obligation bond that will yield $10 billion for a variety of climate resilience efforts, including flood, wildfire, coastal, watershed, water supply, and natural resource management programs. resources.ca.gov/Bonds-Oversight/Proposition-4-Climate-Bond Notes: *If reinstated; BRIC funds were not allocated for 2025 CAL OES SUBMITTAL - JUNE 2026
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4.3 Translating Strategy to Action
As detailed in Section 4.5, the mitigation actions in this 2026 MJHMP are organized into FEMA’s six broad categories, which provide a consistent framework for identifying, evaluating, and prioritizing hazard reduction efforts. These categories include Prevention (PRV), Property Protection (PPRO), Public Education and Awareness (PEA), Natural Resource Protection (NRP), Emergency Services (ES), and Structural Projects (SP). Together, they capture the full range of strategies available to reduce hazard risks in Napa County.

Proposed mitigation actions align with these categories, highlighting both the diversity of approaches and the emphasis on solutions that provide multiple community benefits. This framework ensures that limited resources are directed toward the actions with the greatest potential to reduce risk and strengthen longterm resilience.

Figure 4-1: FEMA’s Six Mitigation Action Categories
Integrating Public Input
As detailed in Section 2.1.2, public participation played a central role in shaping the mitigation action plan by ensuring that the strategies and actions reflect the needs, concerns, and priorities of residents across Napa County. Through the online survey, public outreach, and stakeholder engagement, community members identified both the types of mitigation projects they value most and the barriers they face in taking action themselves.

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Survey results show strong public demand for investments that improve safety, infrastructure resilience, and long-term community preparedness. The most frequently requested actions included improving the damage resistance of utility infrastructure, upgrading bridges and roadways (including evacuation routes), conducting more vegetation management, and ensuring reliable backup power for critical facilities and emergency operations. Additional high priorities were retrofitting and strengthening critical facilities and increasing property owner assistance for hazard mitigation. These findings directly informed the development of county-wide and jurisdiction-specific mitigation actions, ensuring that the final plan addresses the most urgent community needs.

At the same time, the survey highlighted key barriers that prevent residents from advancing mitigation on their own. The most significant challenge was a lack of funding, followed by needs for more information on where to start and physical labor assistance. There were also a significant number of responses (approximately one-quarter) that perceived their property risk as too low to warrant mitigation. Recognizing these constraints, the mitigation strategies and action plans emphasize solutions that provide increased property owner mitigation assistance, shared benefits at the community-scale, and robust public education and outreach.

Other key findings among the comments collected and incorporated into the MJHMP throughout the planning process include:
▪ Wildfire is perceived as the highest threat, followed by drought, extreme heat, and earthquake; dam and slope failure are perceived as the lowest threats.
▪ Most survey respondents (about 85%) believe their property is vulnerable to damage from a natural disaster
▪ Over 20% of survey respondents do not feel that their household or business is prepared for an emergency evacuation.
▪ The most common mitigation actions community members have taken to reduce their property risk are purchasing insurance, installing low-flow plumbing fixtures, and modifying vegetation for drought tolerance or defensible space.
▪ Renters experience additional barriers in mitigating their homes and feel that hazard risks are beyond their control to address.

By integrating community input with technical risk assessment and planning team expertise, the Mitigation Action Plan prioritizes actions that not only reduce hazard exposure but also respond directly to the challenges residents experience. This approach ensures that mitigation is both technically sound and socially responsive, aligning limited resources with the areas of highest public concern and need.

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Figure 4-2: Public Survey Summary
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Action Prioritization
Mitigation actions in the 2026 MJHMP were prioritized based on anticipated risk reduction, alignment with current capabilities and mitigation strategies, furtherance of equitable and multi-benefit outcomes, and collaboration opportunities. Those actions which address the highest priority or multiple hazards with positive cost/benefit ratios and are less reliant on competitive funding sources were given preference, while actions that reliant on substantial investments in capacity-building or on securing outside funding from limited sources were typically given lower priority.

Action priority was ranked on a scale of low to very high and were evaluated against three basic criteria:
▪ Hazard Risk: Actions that address hazards ranked as extreme or high in the jurisdiction’s Risk Matrix were prioritized over those rated as medium or low threats. ▪ Alignment with Existing Efforts: Actions that already align with existing resilience strategies and jurisdictional capabilities and are attainable faster, cheaper, or with less reliance on external inputs were increased in priority.
▪ Equitable and Multi-Benefit Outcomes: Actions that provide multiple community benefits (ecological, social, and economic), address multiple hazard problems, or that can help reduce disparities, improve conditions in disadvantaged communities, or address the needs of vulnerable populations were increased in priority.

This framework ensures that the highest priority actions are realistically achievable during the next five years, reduce hazard risks from the most pressing threats, support or are supported by existing resilience strategies, advance mitigation equitably, and provide multiple benefits. In addition, collaboration opportunities were considered in ranking mitigation actions, further prioritizing those that address crosscutting challenges through shared efforts as discussed in Section 4.4.

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4.4 County-Wide Mitigation Strategy
In recognizing that hazards do not distinguish jurisdictional boundaries and resource limitations, the Steering Group and HMPT determined that a coordinated, county-wide mitigation strategy was needed to address cross-cutting challenges. The County-Wide Mitigation Action Plan (Table 4-3) establishes a unified strategy for reducing risk across all participating jurisdictions. While each jurisdiction faces its own hazards and sets local priorities, many risks overlap and require county-wide coordination to address effectively.

The county-wide mitigation strategy emphasizes actions that strengthen resilience across the entire county, build on local
capabilities, and leverage
inter-jurisdictional and
regional collaboration to
overcome cross-cutting
hazard problems with shared
benefits. This framework
ensures that county-wide
challenges are met with
consistent, equitable, and
coordinated solutions.

Figure 4-3 illustrates the
shared mitigation strategy
concept, showing how the
plan builds on the individual
efforts and strengths of each
participating jurisdiction to
address shared hazard risks.

The strategy and action plan
were developed by the countywide Planning Team through the comprehensive planning
process described in Section

2. All actions presented in the
county-wide action plan are
High Priority. Figure 4-3: County-Wide Mitigation Strategy Diagram CAL OES SUBMITTAL - JUNE 2026
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Table 4-3: County-Wide Mitigation Action Plan
Hazard Key Partners Action Title /
ID Description Mitigation Alternative(s)
All Hazard All
Jurisdictions
Coordinated
CountyWide
Outreach
Strategy
-
ma-AH-CW01
In collaboration with all MJHMP planning
partners, coordinate a county-wide outreach
strategy to enhance public education and
awareness of hazard risks and mitigation
actions through consistent, aligned
messaging. Efforts should leverage trusted
voices and existing networks to reach
diverse communities, using inclusive,
multilingual, and accessible materials
delivered across a variety of platforms.

Develop a suite of ready-to-use outreach
resources and tools that can be tailored to
specific audiences and jurisdictions to
promote sustained engagement and shared
understanding of local hazards and
mitigation opportunities.

PE&A
All Hazard County,
Municipalities,

ACFPD & NCOE
Shelter &
Evacuation
Network
-
ma-AH-CW02
In collaboration with municipal planning
partners and CBOs, identify and retrofit
public and private facilities, such as libraries
and community centers, to serve as
accessible, low-barrier emergency shelters
and cooling centers with options for pets.

Upgrades may include backup power; HVAC,
air filtration, and air conditioning systems;
ADA compliance; and capacity to operate
during heat, cold, smoke, wildfire, severe
weather, and other hazard events while
supporting community outreach and
emergency response operations. Also
improve evacuation routes and support
networks to assist vulnerable populations
such as seniors and those with disabilities.

SP, PPRO,
ES
All Hazard All
Jurisdictions
CountyWide Power
Resilience
-
ma-AH-CW03
In collaboration with all MJHMP planning
partners and PG&E, construct power
redundancy improvements including
emergency interties, microgrid installations,
backup generators or renewable generation
sources, battery storage, and other
improvements for critical facilities and
infrastructure across the county.

SP, PPRO, ES
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Hazard Key Partners Action Title /
ID Description Mitigation Alternative(s)
Wildfire County,
Municipalities,

ACFPD, NCOE,
NapaSan &
Howell
Mountain
Coordinated
Wildfire
Mitigation
-
ma-WF-CW04
In collaboration with regional wildfire
planning partners, implement priority fuel
management, forest health, and watershed
protection projects on public and private
lands through partnerships among local,
regional, state, and private entities, in
alignment with the CWPP. Projects should
advance shared forest health and wildfire
risk reduction priorities to achieve
landscape-scale resilience outcomes by
leveraging cross-jurisdictional coordination,
shared resources, and community outreach
and education.

NRP, PE&A
Drought County,
Municipalities,
NapaSan,
NCOE & Howell
Mountain
Coordinated
Drought
Mitigation
-
ma-DR-CW05
In collaboration with regional water service
and planning partners, plan for and develop
alternative water supplies and system
redundancy improvements, such as
stormwater catchment infrastructure,
groundwater recharge basins, recycling
systems, and emergency interties.

Coordinate public outreach and education
efforts to align messaging and improve
water conservation.

PRV, PE&A,

NRP, SP
Flood, Severe
Weather
(Heavy Rain),
& Climate
Change (Sea
Level Rise)
County,
NCFCWCD, City
of Napa, City of
American
Canyon, NCOE
& NapaSan
Coordinate
Flood & Sea
Level Rise
Mitigation
-
ma-FL-CW06
In collaboration with regional floodplain
management and coastal planning partners,
complete re-mapping of flood and sea level
rise hazards and conduct additional
mitigation projects for flood-prone areas,
infrastructure, and structures exposed to
SLR or not already receiving protection from
Measure "A" Flood Project. Mitigation
projects should include bridge, culvert, and
other drainage and flood control
improvements through a combination of
structural and nature-based solutions.

PRV, SP,

PPRO, NRP
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4.5 Mitigation Action Plan
The Mitigation Action Plan is the roadmap for reducing hazard risk and strengthening resilience across Napa County and all participating jurisdictions. It translates the county-wide goals, range of mitigation alternatives, and prioritization framework into a set of actionable steps designed to safeguard people, property, infrastructure, and natural systems.

The actions in the county-wide plan (Table 4-3), Napa County plan (Table 4-4), and those in Volume 2 annexes are the product of a structured process that combined data from the risk assessment, input from planning partners and stakeholders, and a prioritization framework designed to ensure accountability and transparency. Each action was evaluated against prioritization factors presented previously and accompanied by key details to guide implementation and accountability:
▪ Timeline: Short-term, medium-term, or long-term implementation schedule. ▪ Responsibility: The lead agency or department and supporting partners. ▪ Cost/Benefit Review: A qualitative review of relative costs and benefits. Actions with benefits equal to or greater than their costs are considered cost-beneficial. • Cost: Low (fundable under existing budget), Medium (requires budget adjustment or multi-year allocation), or High (requires new funding source such as grants or bonds). • Benefit: Low (difficult to quantify in short-term), Medium (provides long-term benefits or immediate property risk reduction), or High (provides immediate life-safety and property protection).
▪ Potential Funding Sources: Local resources such as general funds or dedicated fees, as well as state or federal funding sources, including FEMA HMA programs and Cal OES grants.

Together, these elements ensure that the Mitigation Action Plan is not just a list of projects but a carefully prioritized and actionable strategy. By balancing readiness, cost-effectiveness, equity, and strategic alignment, the plan provides a clear pathway for jurisdictions to reduce risk while maximizing co-benefits and shared investment.

Important Note: Recognizing that new needs and priorities may arise as a result of a disaster or other circumstances, the MJHMP partners reserve the right to support new and edit existing actions as necessary, so long as the actions conform to the overall goals of this plan.

Mitigation Action Identification
Each mitigation action in this MJHMP is assigned a unique identification number using alphanumeric characters that denote specific attributes, as illustrated in Figure 4-4. These attributes include the type of hazard being mitigated (e.g., WF for wildfire), an abbreviation for the responsible jurisdiction, and a number to facilitate easy reference and management.

In addition, the mitigation actions encompass both newly developed actions for this plan update and existing actions carried over from previous hazard mitigation plans that were yet to be completed or needed refinement. This is reflected in the identification information for each action as “new” or “existing.” CAL OES SUBMITTAL - JUNE 2026
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Problem statements are similarly assigned a unique identification number, except that instead of beginning with “ma” for mitigation action, they begin with “ps” for problem statement. Problem statements for Napa County are found in the hazard profiles of the risk assessment in Volume 1 (Section 3), and statements for other participating jurisdictions are found in Volume 2.

Figure 4-4: Mitigation Action Number Key
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Table 4-4: Napa County Mitigation Action Plan
Mitigation No. Hazard
Type
Sub-Hazard Mitigation
Type
Year Primary
Agency
Title Description Responsible
Party
Estimated
Cost
Estimated
Benefit
Time
Frame
HMA
Activity
Type
Potential Grant
Source
Priority Related Problem Statements
ma-AH-NCo-4 All Hazard PPRO -
Property
Protection , SP
- Structural
Projects
2020 Napa
County
Power
Resilience
Improvements
Construct or install backup power generators or
renewable generation sources, batteries, and
other power redundancy improvements for
public safety buildings and critical facilities like
fire stations, pump houses, emergency shelters,
cooling centers, and backup Emergency
Command Center locations.

Office of
Emergency
Services
High High 5-10 Years Project HMGP / BRIC ,
General Fund
Medium ps-EQ-NCo-64, ps-EQ-NCo-56,
ps-EQ-YT-72, ps-EQ-NCo-62,
ps-EQ-NCo-78, ps-EQ-NCo-77,
ps-FL-NCo-129, ps-EH-NCo-3,
ps-EH-NCo-10, ps-SW-NCo144, ps-SW-NCo-391, ps-SWNCo-393, ps-SW-NCo-394, psWF-NCo-154 ma-AH-NCo-6 All Hazard PE&A - Public
Education &
Awareness
2020 Napa
County
Comprehensive
All-Hazard
Outreach
Program
In collaboration with municipalities and other
local and regional jurisdictions, coordinate and
develop a comprehensive, county-wide
outreach strategy to enhance public education
and awareness of hazard risks and mitigation
actions through consistent, aligned messaging.

Efforts should leverage trusted voices and
existing networks to reach diverse
communities, using inclusive, multilingual, and
accessible materials delivered across a variety
of platforms and addressing all priority natural
hazards, including wildfire, flood, drought,
earthquake, severe weather, extreme heat, dam
failure, slope failure, and climate change.

Develop annual campaigns (e.g., Natural Hazard
Awareness Week, earthquake or flood education
month, 72-hour kits) and a suite of ready-to-use
outreach resources and tools that can be
tailored to specific audiences and jurisdictions
to promote sustained engagement and shared
understanding of local hazards and mitigation
opportunities.

Office of
Emergency
Services
Medium Medium 3-5 Years Capacity /
Capability
Building

HMGP / BRIC ,
General Fund ,
CalFIRE
High ps-FL-NVC-126, ps-FL-NVC127, ps-FL-NCo-128, ps-DFNCo-385, ps-DF-NCo-387, psDR-NCo-389, ps-EQ-NCo-58, ps-EQ-NCo-62, ps-FL-NCo395, ps-EH-NCo-3, ps-EHNCo-10, ps-EH-NCo-390, psSW-NCo-391, ps-SF-NCo-151, ps-WF-NCo-155, ps-WF-NCo156
ma-AH-NCo-15 All Hazard PPRO -
Property
Protection ,
PE&A - Public
Education &
Awareness ,
ES -
Emergency
Services
2020 Napa
County
Enhance
County-Wide
Shelter
Network
In collaboration with municipalities and other
local partners, identify and retrofit county-,
public agency-, and CBO-owned facilities, such
as libraries and other community centers, to
serve as accessible, low-barrier all-hazard
shelters with options for pets. Upgrades may
include backup power, HVAC and air filtration
systems, ADA compliance improvements, and
capacity to operate during heat, cold, smoke,
wildfire, and other severe weather or hazard
events, while supporting community outreach
and emergency response operations.

Office of
Emergency
Services
High High 3-5 Years Capacity /
Capability
Building

HMGP / BRIC ,
General Fund
High ps-EH-NCo-3, ps-WF-NCo-164,
ps-WF-NCo-14, ps-SW-NCo144, ps-EH-NCo-390, ps-EQNCo-56, ps-DF-NCo-387 ma-AH-NCo-26 All Hazard PRV -
Prevention
2020 Napa
County
All-Hazard
Development
Regulations
Update
Adopt and enforce updated building and
development codes to reduce hazard risks to
people, property, and environmental resources,
including strengthening standards and
enforcement for earthquake safety, water
conservation, stormwater management, slope
stabilization and erosion control, and
protections from other natural hazards.
(Consider timing update with other code
changes for flood, SLR, and wildfire resilience.)
Building,
Planning &
Environmental
Services
Department
Low Medium 1-3 Years Capacity /
Capability
Building

HMGP / BRIC ,
General Fund
Medium ps-CC-NCo-11, ps-CC-NCo-4,
ps-DF-NCo-385, ps-DR-NCo41, ps-EQ-NCo-58, ps-EQ-NCo56, ps-EQ-NCo-392, ps-FLNCo-117, ps-FL-NCo-395, psEH-NCo-10, ps-SW-NCo-130, ps-SF-NCo-151, ps-WF-NCo155
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Mitigation No. Hazard
Type
Sub-Hazard Mitigation
Type
Year Primary
Agency
Title Description Responsible
Party
Estimated
Cost
Estimated
Benefit
Time
Frame
HMA
Activity
Type
Potential Grant
Source
Priority Related Problem Statements
ma-CC-NCo-1 Climate
Change
Agricultural
Impacts
PRV -
Prevention ,
PE&A - Public
Education &
Awareness
2020 Napa
County
Agricultural
Sector
Vulnerability
Assessment,
Disaster
Planning &
Training
In collaboration with local farmers and wineries,
conduct a climate change risk assessment for
the agricultural industry and develop mitigation
strategies that support disaster management at
the local levels. Provide agricultural disaster
training and networking opportunities for
farmers and agricultural regulatory agencies.

Agricultural
Commissioner's
Office
Low Medium 1-3 Years Capacity /
Capability
Building
Internal Funding High ps-CC-NCo-0, ps-CC-NCo-1,
ps-CC-NCo-7, ps-DR-NCo-388,
ps-DR-NCo-389, ps-EH-NCo-9,
ps-EH-NCo-390, ps-SW-NCo393, ps-WF-NCo-14
ma-CC-NCo-13 Climate
Change
Sea Level
Rise
PRV -
Prevention ,
PPRO -
Property
Protection
2020 Napa
County
Sea Level Rise
Assessment &
Code Update
In collaboration with ABAG, DWR, and other
regional partners, conduct a sea level rise
assessment update that integrates the best
available data and modeling, with consideration
of recent flood mitigation projects and tidal
influences. Adopt updated and new
development standards based on the
assessment to help protect and mitigate the
long-term impacts of sea level rise and other
climate change-driven shoreline hazards (e.g.,
tidal flooding, erosion, storm surge).

Public Works
Department,
Planning,
Building &
Environmental
Services
Department
Medium Medium 3-5 Years Project HMGP / BRIC ,
General Fund
Medium ps-CC-NCo-4, ps-CC-NCo-6,
ps-CC-NCo-7, ps-FL-NCo-395,
ps-FL-NCo-117, ps-SW-NCo130
ma-DF-NCo-55 Dam
Failure
PRV -
Prevention ,
ES -
Emergency
Services
2020 Napa
County
Dam Failure
Assessment &
Warning
System
Update and improve risk assessments for high
hazard and poor condition dams that threaten
county populations, properties, facilities, or
infrastructure, and construct, install, and
maintain warning gauges on high-priority dams
as the opportunity or need arises. Design and
implement a county-wide dam failure warning
system in collaboration with other jurisdictions,
dam owners/operators, and state and regional
partners to improve warning procedures and
time for everyone within a dam inundation
zone, especially those located in areas at risk of
cascading failures.

Office of
Emergency
Services, Public
Works
Department
High Medium 3-5 Years Capacity /
Capability
Building

HMGP / BRIC ,
General Fund
Medium ps-DF-CL-24, ps-DF-NCo-25,
ps-DF-CL-26, ps-DF-NVC-28,
ps-DF-YT-29, ps-DF-YT-30,
ps-DF-NCOE-31, ps-DF-AC-32,
ps-DF-AC-33, ps-FL-NCo-110,
ps-FL-YT-114, ps-DF-NCo-384,
ps-DF-NCo-385, ps-DF-NCo386, ps-DF-NCo-387
ma-DR-NCo-18 Drought NRP - Natural
Resource
Protection , SP
- Structural
Projects
2020 Napa
County
Water Supply
Redundancy
Improvements
Develop alternative water supplies to augment
single sources of water delivery, work with
partner agencies to install emergency interties,
and construct groundwater recharge
infrastructure (e.g., rainwater catchment
systems, recharge basins).

Public Works
Department
High High 5-10 Years Project HMGP / BRIC ,
General Fund
High ps-CC-NCo-11, ps-CC-NCo-1,
ps-DR-NCo-41, ps-DR-NCo388, ps-DR-NCo-389
ma-DR-NCo-24 Drought PPRO -
Property
Protection ,
NRP - Natural
Resource
Protection
2020 Napa
County
Water
Efficiency
Improvements
Conduct water efficiency improvements for
county properties and facilities, including
replacing and installing new landscaping for
drought tolerance, auditing water usage, and
installing/upgrading irrigation and plumbing
fixtures to reduce waste.

Public Works
Department
High High 3-5 Years Project HMGP / BRIC ,
General Fund
High ps-DR-NCo-41, ps-DR-AC-42,
ps-DR-CL-45, ps-DR-NCOE-44,
ps-DR-NCo-389
ma-EQ-NCo-37 Earthquake PPRO -
Property
Protection ,
PE&A - Public
Education &
Awareness
2020 Napa
County
Earthquake
Hardening
Assistance
Program
Encourage privately owned critical and largecapacity facilities (e.g. houses of worship, hotels, other gathering facilities) to conduct seismic
evaluations and needed retrofits. Conduct
targeted outreach and develop a technical
assistance program to guide property owners
through the process. Provide retrofit incentives
as feasible.

Building,
Planning &
Environmental
Services
Department
Medium High 3-5 Years Capacity /
Capability
Building

HMGP / BRIC ,
General Fund
Medium ps-EQ-NCo-58, ps-EQ-NCo-62,
ps-EQ-NCo-63, ps-EQ-NCo-56,
ps-EQ-NCo-57, ps-EQ-NCo392
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Mitigation No. Hazard
Type
Sub-Hazard Mitigation
Type
Year Primary
Agency
Title Description Responsible
Party
Estimated
Cost
Estimated
Benefit
Time
Frame
HMA
Activity
Type
Potential Grant
Source
Priority Related Problem Statements
ma-EQ-NCo-38 Earthquake PPRO -
Property
Protection , SP
- Structural
Projects
2020 Napa
County
Facilities &
Infrastructure
Seismic
Hardening
Projects
Retrofit and harden county-owned critical
facilities and infrastructure to increase their
ability to withstand earthquakes, including
vulnerable water, sewer, natural gas, and
transportation lines.

Public Works
Department
High High 5-10 Years Project HMGP / BRIC ,
General Fund
High ps-EQ-NCo-56, ps-EQ-NCo-57,
ps-EQ-NCo-61, ps-EQ-NCo-77,
ps-EQ-NCo-60, ps-EQ-NCo-64,
ps-EQ-NCo-65, ps-EQ-NCo392
ma-EH-NCo-16 Extreme
Heat
PPRO -
Property
Protection ,
PE&A - Public
Education &
Awareness
2020 Napa
County
Extreme Heat
Mitigation
Assistance
Program
Develop an extreme heat mitigation assistance
program for seniors, low-income households,
and other populations disproportionately
vulnerable to heat events, including technical
and financial aid for air conditioning
installation/replacement, tree planting, and
home energy efficiency upgrades.

Housing &
Community
Services
Department
Medium High 3-5 Years N/A HMGP / BRIC ,
General Fund
Medium ps-CC-NCo-8, ps-EH-NCo-10,
ps-CC-YT-12, ps-EH-NCo-3,
ps-EH-NCo-9, ps-EH-NCo-390
ma-FL-NCo-51 Flood PPRO -
Property
Protection ,
NRP - Natural
Resource
Protection , SP
- Structural
Projects
2013 Napa
County
Flood Hazard
Mapping
Update &
Mitigation
Projects
In coordination with NCFCWCD and DWR,
complete re-mapping of flood hazards and
conduct additional flood mitigation projects for
flood-prone areas, infrastructure, and structures
not already receiving protection from Measure
"A" Flood Project and for Repetitive Loss
properties. Mitigation projects should include
bridge, culvert, and other drainage and flood
control improvements through a combination of
structural and nature-based solutions.

Public Works
Department,
Building,
Planning &
Environmental
Services
Department
High High 3-5 Years Project HMGP / BRIC ,
FMA , General
Fund
High ps-FL-NCFC-103, ps-FL-NCo119, ps-FL-NCo-129, ps-FLNCo-395, ps-SW-NCo-130, psSW-NCo-144, ps-CC-NCo-4 ma-FL-NCo-52 Flood PPRO -
Property
Protection ,
PE&A - Public
Education &
Awareness
2020 Napa
County
Flood Hazard
Education &
Assistance
program
Develop a flood-specific public outreach and
education program that increases participation
in the NFIP; informs property owners located in
areas exposed to future sea level rise or
dam/levee inundation about voluntary flood
insurance (preferred risk policies); and
increases awareness of public efforts and
property owner options to mitigate current and
future flood hazards. Develop additional support
resources, technical and financial assistance,
and incentives for individual property
mitigation.

Building,
Planning &
Environmental
Services
Department
Medium High 3-5 Years Capacity /
Capability
Building

HMGP / BRIC ,
FMA , General
Fund
High ps-DF-NCo-25, ps-DF-SH-27,
ps-FL-NCo-110
ma-FL-NCo-54 Flood PRV -
Prevention
2020 Napa
County
Floodplain
Development
Standards
Update
Update and strengthen the regulations for
development in flood-prone areas, including
adopting higher standards such as freeboard,
flood storage, setbacks and fill restrictions,
lower substantial damage or improvement
thresholds, and a stream channel ordinance
that places drainage maintenance responsibility
on property owners with county enforcement
power, in support of a no-adverse-impact
philosophy and improving the county CRS
rating for reduced insurance costs.

Building,
Planning &
Environmental
Services
Department
High High 1-3 Years Capacity /
Capability
Building

HMGP / BRIC ,
General Fund
Medium ps-FL-NCo-117, ps-CC-NCo-4,
ps-CC-NCo-7, ps-DF-NCo-385,
ps-FL-NCo-119, ps-FL-NCo395, ps-FL-NCo-128, ps-SWNCo-130, ps-SW-NCo-144 ma-FL-NCo-59 Flood PPRO -
Property
Protection
2020 Napa
County
Farmworker
Centers
Relocation
Relocate the three farmworker centers exposed
to flood risks to areas that are not exposed to
hazards or that are effectively mitigated.

Agricultural
Commissioner's
Office, Housing &
Community
Services
Department
High High 3-5 Years Project HMGP / BRIC ,
FMA , General
Fund
High ps-FL-NCo-102
CAL OES SUBMITTAL - JUNE 2026
Item #6.5.

HAZARD MITIGATION PLAN 2026 UPDATE

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NAPA COUNTY | HAZARD MITIGATION PLAN 2026 UPDATE
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Mitigation No. Hazard
Type
Sub-Hazard Mitigation
Type
Year Primary
Agency
Title Description Responsible
Party
Estimated
Cost
Estimated
Benefit
Time
Frame
HMA
Activity
Type
Potential Grant
Source
Priority Related Problem Statements
ma-SW-NCo-57 Severe
Weather
Heavy Rain PRV -
Prevention ,
PPRO -
Property
Protection ,
NRP - Natural
Resource
Protection
2020 Napa
County
Drainage
Infrastructure
Inventory &
Capacity
Improvements
In partnership with NCFCWCD, identify, assess,
and upgrade undersized culverts and other
stormwater infrastructure (e.g., Milton culvert,
stormwater basins) to manage high-intensity
rainfall under current and future projected
conditions, including through nature-based and
green infrastructure solutions. Complete an
inventory of all publicly-owned stormwater
facilities and establish a priority list for
replacements and other improvements that
account for fish passage, flood depth reduction,
sea level rise, tidal influences, and future losses
avoided.

Public Works
Department
High High 3-5 Years Project HMGP / BRIC ,
FMA , General
Fund
High ps-FL-NCo-129, ps-CC-NCo-4,
ps-CC-NCo-7, ps-DF-NCo-385,
ps-FL-NCo-102, ps-FL-NCo110, ps-FL-NCo-119, ps-FLNCo-395, ps-SW-NCo-130, psSW-NCo-144 ma-SF-NCo-84 Slope
Failure
PPRO -
Property
Protection
2020 Napa
County
Slope Failure
Risk Mapping &
Stabilization
Projects
Conduct a county-wide mapping study of high
slope failure risk areas, especially near critical
assets and along major access routes. Establish
a priority list of slope failure locations and
implement slope stabilization projects in the
highest risk areas.

Public Works
Department
High High 3-5 Years Project HMGP / BRIC ,
General Fund
Low ps-SF-NCo-151, ps-SF-NCo152, ps-SF-NCo-396
ma-SF-NCo-85 Slope
Failure
PPRO -
Property
Protection
2020 Napa
County
Angwin VFD
Protections
Construct a slope stabilization project to protect
the Angwin VFD storage facility.

Fire Department,
Public Works
Department
Medium Medium 1-3 Years Project N/A High ps-SF-NCo-152, ps-SF-NCo396 ma-WF-NCo-90 Wildfire PPRO -
Property
Protection ,
PE&A - Public
Education &
Awareness ,
NRP - Natural
Resource
Protection , ES
- Emergency
Services
2020 Napa
County
Wildfire
Mitigation
Assistance
Program
Enhance the existing wildfire mitigation
assistance program through assistance capacity
improvements and additional outreach. Improve
technical and financial assistance programs
with Napa Firewise for fuel management,
access improvements, proper addressing
installation, structure hardening, and other
mitigation measures. Support efforts by also
fostering and forming additional neighborhoodbased Firewise Councils through grant writing.

Fire Department High High 1-3 Years N/A HMGP / BRIC ,
General Fund ,
CalFIRE
High ps-WF-CL-179, ps-WF-NCo164, ps-WF-NCo-165, ps-WFNCo-166, ps-WF-NCo-167, psWF-NCo-168, ps-WF-NCo-169, ps-WF-NCo-170, ps-WF-AC173, ps-WF-YT-176, ps-WF-CL183, ps-WF-NCo-14, ps-WFNCo-155, ps-WF-NCo-156, psWF-NCo-172, ps-WF-NCo-181 ma-WF-NCo-94 Wildfire PPRO -
Property
Protection , ES
- Emergency
Services , SP -
Structural
Projects
2013 Napa
County
Facility &
Infrastructure
Wildfire
Hardening
Projects
Retrofit critical facilities and infrastructure with
fire resistant materials and other structure
hardening methods, improve emergency access
and evacuation routes (e.g., Howell Mountain
Rd.), create defensible space, and install
emergency water supplies in strategic locations.

Work with property owners of essential
facilities like adult and childcare centers and
with utility providers, especially power.

Fire Department,
Public Works
Department
High High 5-10 Years Project HMGP / BRIC ,
General Fund ,
CalFIRE
High ps-WF-NCo-171, ps-WFNCOE-178, ps-WF-NVC-180,
ps-WF-NCo-14, ps-WF-NCo153, ps-WF-NCo-154
ma-WF-NCo-95 Wildfire PRV -
Prevention ,
NRP - Natural
Resource
Protection
2013 Napa
County
Advanced
Ignition & Fuel
Management
Enforcement
Develop an enhanced wildfire education and
enforcement program that focused on seasonal
vegetation management and weed abatement
as well as the human causes of ignition.

Address these problems through regular
education and outreach and seasonal
enforcement actions, including strict property
inspection, warning, fining, and cleanup
procedures and vigorous prosecution of arson.

Napa County Fire Medium Medium 3-5 Years Capacity /
Capability
Building

HMGP / BRIC ,
General Fund ,
CalFIRE
High ps-WF-NCo-155, ps-WF-NCo181, ps-WF-SH-198, ps-WFNCo-14, ps-WF-NCo-154, psWF-NCo-156, ps-WF-NCo-164, ps-WF-NCo-172
CAL OES SUBMITTAL - JUNE 2026
Item #6.5.

NAPA COUNTY | HAZARD MITIGATION PLAN 2026 UPDATE
HAZARD MITIGATION PLAN 2026 UPDATE

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4-31
Mitigation No. Hazard
Type
Sub-Hazard Mitigation
Type
Year Primary
Agency
Title Description Responsible
Party
Estimated
Cost
Estimated
Benefit
Time
Frame
HMA
Activity
Type
Potential Grant
Source
Priority Related Problem Statements
ma-WF-NCo-96 Wildfire NRP - Natural
Resource
Protection
2020 Napa
County
Enhanced Fuel
Management
Program
Complete vegetation management projects as
prescribed in the CWPP, such as shaded fuel
breaks, prescribed burns, and roadside
treatments, and establish a long-term
maintenance program.

Fire Department Medium High 3-5 Years Capacity /
Capability
Building

HMGP / BRIC ,
General Fund ,
CalFIRE
High ps-WF-NCo-182, ps-WF-NCo181, ps-WF-NCo-172, ps-WFNCo-164, ps-WF-NCo-156, psWF-NCo-154, ps-WF-NCo-14 CAL OES SUBMITTAL - JUNE 2026
Item #6.5.

HAZARD MITIGATION PLAN 2026 UPDATE

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PAGE INTENTIONALLY BLANK
CAL OES SUBMITTAL - JUNE 2026
Item #6.5.

NAPA COUNTY | HAZARD MITIGATION PLAN 2026 UPDATE
HAZARD MITIGATION PLAN 2026 UPDATE

NAPA COUNTY
4-1

4.6 Status of Previous Mitigation Actions
In 2020, Napa County adopted its previous FEMA-approved MJHMP. This 2026 plan represents a comprehensive update from that previous MJHMP, as discussed in Section 1.5. Table 4-5 provides status updates for all of the previous mitigation actions in Napa County's 2020 MJHMP, from which many of the mitigation actions in Table 4-4 were sourced and revised.

Table 4-5: Status of Previous Napa County Mitigation Actions Mitigation
No.

Hazard
Type
Status Year Primary Agency Title/Description Reason Completed ma-WFNCo-91Wildfire Completed 2013 Napa County Develop & conduct a Defensible Space
community education
program.

Program established through Napa
Firewise
ma-WFNCo-92Wildfire Completed 2013 Napa County Draft & promulgate Defensible Space
Ordinance.

Ordinance update completed
ma-AGNCo-2Ag Disaster Cancelled 2020 Napa County Offer agricultural disaster training and networking
opportunities for farmers
and ag regulatory agencies.

NC-56-2020, NC-27-2020, NC-57-
2020 combined and revised
ma-AHNCo-5All Hazard Cancelled 2020 Napa County Construct/Install back up power generators for fire
stations, pump houses,
emergency shelters and
cooling centers.

NC-09-2013, NC-11-2020, NC-15-2020
combined and revised
ma-CCNCo-14Climate
Change
Cancelled 2020 Napa County Create an outreach plan to
inform residents about
County efforts to boost
resilience to sea-level rise
NC-30-2020, NC-31-2020, NC-21-
2020 combined and revised
ma-CCNCo-17Climate
Change
Cancelled 2020 Napa County Support risk assessments
for the agriculture and wine
industries.

NC-56-2020, NC-27-2020, NC-57-
2020 combined and revised
ma-CCNCo-19Climate
Change
Cancelled 2020 Napa County Construct rainwater
catchment systems to
recharge groundwater in
government ROWs.

NC-28-2020 & NC-29-2020
combined and revised
ma-DFNCo-120Dam
Failure
Cancelled 2020 Napa County Develop and implement a
County-wide warning
system for dam failure,
including all HMP
jurisdictions as secondary
participants.

NC-34-2020, NC-35-2020, NC-200-
2020 combined and revised
ma-DRNCo-23Drought Cancelled 2020 Napa County Develop a public education campaign to encourage
water conservation during
drought.

NC-32-2020, NC-10-2013, NC-12-
2020, NC-13-2020, NC-16-2020
combined and revised
ma-DRNCo-25Drought Cancelled 2020 Napa County Install drought tolerant landscaping at
government-owned
facilities.

NC-17-2020 & NC-18-2020 combined
and revised
CAL OES SUBMITTAL - JUNE 2026
Item #6.5.

HAZARD MITIGATION PLAN 2026 UPDATE

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NAPA COUNTY | HAZARD MITIGATION PLAN 2026 UPDATE
4-2
Mitigation
No.

Hazard
Type
Status Year Primary Agency Title/Description Reason Completed ma-DRNCo-27Drought Cancelled 2020 Napa County Adopt a water conservation ordinance to limit outdoor
watering for commercial
and residential properties.

NC-22-2020, NC-54-2020, NC-23-
2020 combined and revised
ma-EQNCo-36Earthquake Cancelled 2013 Napa County Earthquake month public education program.

Develop a comprehensive
public outreach program for
earthquake risk reduction
for Napa County Residents.

NC-32-2020, NC-10-2013, NC-12-
2020, NC-13-2020, NC-16-2020
combined and revised
ma-EQNCo-39Earthquake Cancelled 2020 Napa County Adopt and enforce updated building codes to reduce
earthquake damage to
structures.

NC-22-2020, NC-54-2020, NC-23-
2020 combined and revised
ma-FLNCo-53Flood Cancelled 2020 Napa County Increase participation in the NFIP.

NC-30-2020, NC-31-2020, NC-21-
2020 combined and revised
ma-FLNCo-56Flood Cancelled 2020 Napa County Improve risk assessments for dams located within the
county.

NC-34-2020, NC-35-2020, NC-200-
2020 combined and revised
ma-FLNCo-58Flood Cancelled 2020 Napa County Create an inventory and prioritize culvert
replacements, considering
fish passage, flood depth
reduction, and loss
prevention.

NC-37-2020, NC-38-2020, NC-48-
2020 combined and revised
ma-FLNCo-60Flood Cancelled 2020 Napa County Elevate and or retrofit bridges, culverts to allow
proper stormwater / 100-YR
flows.

NC-01-2013, NC-47-2020, NC-46-
2020 combined and revised
ma-FLNCo-61Flood Cancelled 2020 Napa County Mitigate flood risk to NFIP repetitive loss properties.

NC-01-2013, NC-47-2020, NC-46-
2020 combined and revised
ma-FLNCo-62Flood Cancelled 2020 Napa County Construct / improve stormwater basins Countywide to accomplish 100-YR
protection .

NC-37-2020, NC-38-2020, NC-48-
2020 combined and revised
ma-FLNCo-63Flood Cancelled 2020 Napa County Adopt stricter regulatory standards to reduce flood
risk and support noadverse-impact floodplain
management.

NC-33-2020, NC-50-2020 combined
and revised
ma-PNNCo-77Pandemic Cancelled 2020 Napa County Increase the capacity of existing hospitals through
retrofits or upgrades such
as isolation wings.

Pandemic not profiled
ma-PNNCo-78Pandemic Cancelled 2020 Napa County Retrofit critical care facilities with enhanced
HVAC and isolation areas.

Pandemic not profiled
ma-SWNCo-81Severe
Weather
Cancelled 2020 Napa County Organize outreach to
vulnerable populations,
including establishing and
promoting accessible
shelters in the community.

NC-32-2020, NC-10-2013, NC-12-
2020, NC-13-2020, NC-16-2020
combined and revised
CAL OES SUBMITTAL - JUNE 2026
Item #6.5.

NAPA COUNTY | HAZARD MITIGATION PLAN 2026 UPDATE
HAZARD MITIGATION PLAN 2026 UPDATE

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4-3
Mitigation
No.

Hazard
Type
Status Year Primary Agency Title/Description Reason Completed ma-SWNCo-82Severe
Weather
Cancelled 2020 Napa County Develop a public
information campaign on
72-hour kits.

NC-32-2020, NC-10-2013, NC-12-
2020, NC-13-2020, NC-16-2020
combined and revised
ma-SWNCo-83Severe
Weather
Cancelled 2020 Napa County Procure and maintain
backup generators for
community centers, town
halls, and water treatment
plants used as Emergency
Command Centers.

NC-09-2013, NC-11-2020, NC-15-2020
combined and revised
ma-WFNCo-93Wildfire Cancelled 2013 Napa County Foster & form neighborhood based Firewise Councils
through grant writing.

NC-06-2013, NC-03-2020, NC-53-
2020 combined and revised
ma-WFNCo-97Wildfire Cancelled 2020 Napa County Retrofit care facilities (adult care, child care) with fireresistant materials and or
create defensible space
around structures.

NC-07-2013, NC-55-2020, NC-44-
2020, NC-58-2020 combined and
revised
ma-WFNCo-98Wildfire Cancelled 2020 Napa County Complete vegetation management projects as
prescribed in CWPPs.

NC-19-2020, NC-45-2020, NC-49-
2020 combined and revised
ma-WFNCo-99Wildfire Cancelled 2020 Napa County Construct shaded fuel breaks and complete
roadside treatment projects
as prescribed in CWPPs.

NC-19-2020, NC-45-2020, NC-49-
2020 combined and revised
ma-WFNCo-100Wildfire Cancelled 2020 Napa County Install proper addressing in rural areas to assist in
wildfire emergencies.

NC-06-2013, NC-03-2020, NC-53-
2020 combined and revised
ma-WFNCo-101Wildfire Cancelled 2020 Napa County Work with utility providers to move above ground lines
underground.

NC-07-2013, NC-55-2020, NC-44-
2020, NC-58-2020 combined and
revised
ma-WFNCo-102Wildfire Cancelled 2020 Napa County Construct or improve egress for wildfire emergencies in
wildland urban interface
(WUI) areas.

NC-07-2013, NC-55-2020, NC-44-
2020, NC-58-2020 combined and
revised
ma-AHNCo-4All Hazard Ongoing 2020 Napa County Power Resilience Improvements
Revised
ma-AHNCo-6All Hazard Ongoing 2020 Napa County Comprehensive All-Hazard Outreach Program
Revised
ma-CCNCo-15All Hazard Ongoing 2020 Napa County Enhance County-Wide Shelter Network
Revised
ma-DRNCo-26All Hazard Ongoing 2020 Napa County All-Hazard Development Regulations Update
Revised
ma-AGNCo-1Climate
Change
Ongoing 2020 Napa County Agricultural Sector
Vulnerability Assessment,
Disaster Planning &
Training
Revised
ma-CCNCo-13Climate
Change
Ongoing 2020 Napa County Sea Level Rise Assessment
& Code Update
Revised
ma-FLNCo-55Dam
Failure
Ongoing 2020 Napa County Dam Failure Assessment &
Warning System
Revised
ma-CCNCo-18Drought Ongoing 2020 Napa County Water Supply Redundancy Improvements
Revised
CAL OES SUBMITTAL - JUNE 2026
Item #6.5.

HAZARD MITIGATION PLAN 2026 UPDATE

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NAPA COUNTY | HAZARD MITIGATION PLAN 2026 UPDATE
4-4
Mitigation
No.

Hazard
Type
Status Year Primary Agency Title/Description Reason Completed ma-DRNCo-24Drought Ongoing 2020 Napa County Water Efficiency Improvements
Revised
ma-EQNCo-37Earthquake Ongoing 2020 Napa County Earthquake Hardening Assistance Program
Revised
ma-EQNCo-38Earthquake Ongoing 2020 Napa County Facilities & Infrastructure Seismic Hardening Projects
Revised
ma-FLNCo-51Flood Pending 2013 Napa County Flood Hazard Mapping Update & Mitigation
Projects
Revised
ma-FLNCo-52Flood Ongoing 2020 Napa County Flood Hazard Education & Assistance program
Revised
ma-FLNCo-54Flood Ongoing 2020 Napa County Floodplain Development Standards Update
Revised
ma-FLNCo-59Flood Ongoing 2020 Napa County Farmworker Centers Relocation
Revised
ma-CCNCo-16High Heat Ongoing 2020 Napa County Extreme Heat Mitigation Assistance Program
Revised
ma-FLNCo-57Severe
Weather
Ongoing 2020 Napa County Drainage Infrastructure
Inventory & Capacity
Improvements
Revised
ma-SFNCo-84Slope
Failure
Ongoing 2020 Napa County Slope Failure Risk Mapping
& Stabilization Projects
Revised
ma-SFNCo-85Slope
Failure
Ongoing 2020 Napa County Angwin VFD Protections Revised ma-WFNCo-90Wildfire Ongoing 2020 Napa County Wildfire Mitigation Assistance Program
Revised
ma-WFNCo-94Wildfire Ongoing 2013 Napa County Facility & Infrastructure Wildfire Hardening Projects
Revised
ma-WFNCo-95Wildfire Ongoing 2013 Napa County Advanced Ignition & Fuel Management Enforcement
Revised
ma-WFNCo-96Wildfire Ongoing 2020 Napa County Enhanced Fuel Management Program
Revised
CAL OES SUBMITTAL - JUNE 2026
Item #6.5.

NAPA COUNTY | HAZARD MITIGATION PLAN 2026 UPDATE
HAZARD MITIGATION PLAN 2026 UPDATE

NAPA COUNTY
5-1
Section 5.Works Cited
(2014). Retrieved from National Climate Assessment: https://nca2014.globalchange.gov/ ACS 5-Year. (2022). US Census Bureau American Community Survey 5-Year Estimates.

AGI. (2023). Landslides. American Geosciences Institute. Retrieved from https://profession.americangeosciences.org/society/intersections/landslides Association of Bay Area Governments. (2014, July 21). Napa County Earthquake Hazard. Retrieved from Association of Bay Area Governments Resilience Program:
http://resilience.abag.ca.gov/earthquakes/napa/
Association of State Dam Safety Officials. (2024, Novmeber). Dam Failures and Incidents. Retrieved from https://damsafety.org/dam-failures
Beacon Economics. (2018). Sonoma County Complex FIres: Housing and Fiscal Impact Report. Santa Rosa, Cali.: Sonoma County Economic Development Board. Retrieved 0126 2020, from file:///C:/Users/SwingLaptop/Downloads/Sonoma%20County%20Complex%20Fires%20Housing%20and%20Fiscal%20Imp act%20Report%202018.pdf
Bole, A., Crimmins, A., Glass, G., Saha, S., Shimamoto, M. M., Trtanj, J., & White-Newsome, J. L. (2018).

Chapter 14: Human Health. In D. C. Reidmiller (Ed.), Impacts, Risks, and Adaptation in the United States: Fourth National Climate Assessment, Volume II. Washington, DC, USA: U.S. Global Change Research Program. doi:10.7930/NCA4.2018
Cal Fire. (2018, September 3). Incident Information. Retrieved from Cal Fire:
http://cdfdata.fire.ca.gov/incidents/incidents_cur_search_results?search=napa&submit=Search Cal. Dep't of Water Resources. (2015). California's Most Significant Droughts: Comparing Historical and Recent Conditions.

Cal. Dep't of Water Resources. (2019). Division of Safety of Dams. Retrieved Jan. 30, 2020, from https://water.ca.gov/Programs/All-Programs/Division-of-Safety-of-Dams (2021). California Drought Contingency Plan.

California Energy Comission. (2018). Electricity Demand Changes and Grid Infrastructure Vulnerabilities in LA County by 2060: Policy Brief. Retrieved from https://www.ioes.ucla.edu/wpcontent/uploads/ElectricityDemandandGridVulnerabilityPolicyBrief.pdf California Office of Environmental Health Hazard Assessment. (2019). Heat Related Mortality and Morbidity. Retrieved 04 02, 2021, from https://oehha.ca.gov/epic/impacts-biological-systems/heatrelated-mortality-and-morbidity CAL OES SUBMITTAL - JUNE 2026
Item #6.5.

HAZARD MITIGATION PLAN 2026 UPDATE

NAPA COUNTY
NAPA COUNTY | HAZARD MITIGATION PLAN 2026 UPDATE
5-2
CalOES. (2018). California State Hazard Mitigation Plan.

CalOES. (2025). Dam Safety Planning. Retrieved from Cal OES: https://www.caloes.ca.gov/office-of-thedirector/operations/planning-preparedness-prevention/planning-preparedness/dam-safetyplanning/ CDC. (2020, December 10). Disparities in Deaths from COVID-19. Retrieved from https://www.cdc.gov/coronavirus/2019-ncov/community/health-equity/racial-ethnicdisparities/disparities-deaths.html CDC. (2021). Extreme Heat. Retrieved 04 01, 2021, from
https://www.cdc.gov/disasters/extremeheat/index.html
County, L. A. (2016). Municipal Service Review and Sphere of Influence Update Checklist for Napa County Flood Control and Water Conservation District.

Disasters Are Us. (n.d.). Heat Wave. Retrieved 05 08, 2020, from http://www.disastersrus.org/emtools/Heatwave/heatwave.htm DRU. (2026). Demographics. Retrieved from State of California Department of Finance:
https://dof.ca.gov/forecasting/demographics/
DWR. (2025). California Water Plan. Retrieved from California Department of Water Resources:
https://water.ca.gov/Programs/California-Water-Plan
DWR. (2025). Division of Safety of Dams. Retrieved Jan. 30, 2020, from https://water.ca.gov/programs/allprograms/division-of-safety-of-dams DWR. (2025). Urban Water Management Plans. Retrieved from California Department of Water Resources:
https://water.ca.gov/Programs/Water-Use-And-Efficiency/Urban-Water-Use-Efficiency/UrbanWater-Management-Plans Ebi, K., Balbus, J., Luber, G., Bole, A., Crimmins, A., Glass, G., . . . White-Newsome, J. (2018). Human Health. In D. Reidmiller, C. Avery, D. Easterling, K. Kunkel, K. Lewis, T. Maycock, & B. Stewart (Eds.), Impacts, Risks, and Adaptation in the United States: Fourth National Climate Assessment, Volume II (pp. 572-603). Washington, DC, USA: U.S. Global Change Research Program. doi:10.7930/NCA4.2018.CH14 EPA. (2021). Learn About Environmental Justice.

EPA. (2024, August 20). Learn About Heat Islands. Retrieved from https://www.epa.gov/heatislands/learnabout-heat-islands#_ftn1 Federal Highway Administration. (2013). A Guide for Maintaining Pedestrian Facilities for Enhanced Safety. Retrieved 04 02, 2021, from
https://safety.fhwa.dot.gov/ped_bike/tools_solve/fhwasa13037/chap3.cfm CAL OES SUBMITTAL - JUNE 2026
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HAZARD MITIGATION PLAN 2026 UPDATE

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5-3
Fothergill, A. M. (1999). Race, ethnicity and disasters in the United States: A review of the literature.

Disasters. 23(2), 156-173.

Graham, B. a. (1988). Assessing the Threat to Life from Dam Failure. Water Resources Bulletin, vol. 24, no. 6.

HHS. (2020). Access and Functional Needs. (U. D. Services, Producer) Retrieved from Public Health Emergency: https://www.phe.gov/Preparedness/planning/abc/Pages/afn-guidance.aspx Hoffman, J. S., Shandas, V., & Pendleton, N. (2020). The Effects of Historical Housing Policies on Resident Exposure to Intra-Urban Heat: A Study of 108 US Urban Areas. Climate, 8(1), 12-27. doi:https://doi.org/10.3390/cli8010012
Howell, J., & Elliot, J. R. (2019). Damages Done: The Longitudinal impacts of Natural Hazards on Wealth inequity in the United States. Social Problems, 448-467.

Hulley, G. C., Dousset, B., & Kahn, B. H. (2020, July). Rising Trends in Heatwave Metrics Across Southern California. Earth's Future, 8(7). doi:10.1029/2020EF001480 Krause, E., & Reeves, R. (2017, Sept 18). Hurricans hit the poor the hardest. Retrieved from Bookings Institute: https://www.brookings.edu/blog/social-mobility-memos/2017/09/18/hurricanes-hit-thepoor-the-hardest/ Lenhard, M. (2019, Nov. 26). How the California Wildfires are Impacting Tourism. Skift.com. Retrieved Jan. 26, 2020, from https://skift.com/2019/11/26/how-the-california-wildfires-are-impacting-tourism/ Lutz, H. (2018, February 21). Napa grapegrowers brace for extended frost season, with little rain. Retrieved from Napa Valley Register: https://napavalleyregister.com/news/local/napa-grapegrowers-bracefor-extended-frost-season-with-little-rain/article_74a4eca7-b723-5ebd-abdf-61a2ba7e4958.html Makwana, N. (2019). Disaster and its impact on mental health: A narrative review. Retrieved 08 31, 2021, from https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6857396/ Manconi, A. e. (2016). Real-time detection, location, and characterization of Rockslides using broadband regional seismic networks. Retrieved from
https://agupubs.onlinelibrary.wiley.com/doi/pdf/10.1002/2016GL069572 Napa County. (2024). Napa County Farmworker Housing Needs & Impacts Assessment.

Napa County. (2026). Napa County Baseline Data Report: Community and Public Health. (2018). Napa County Climate Action Plan. Retrieved from https://www.countyofnapa.org/DocumentCenter/View/9247/Revised-Draft-CAP-PDF (2013). Napa County Operational Area Hazard Mitigation Plan 2013 Update.

CAL OES SUBMITTAL - JUNE 2026
Item #6.5.

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NAPA COUNTY
NAPA COUNTY | HAZARD MITIGATION PLAN 2026 UPDATE
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Napa Dep't of Ag./ Sealer of Weights & Measures. (2017). Napa County Agricultural Crop Report. Retrieved from https://www.countyofnapa.org/DocumentCenter/View/13105/2017-Crop-Report-English Napa Firewise. (2021). Napa County Community Wildfire Protection Plan (CWPP).

Napa Valley Subbasin. (2022). Napa Valley Subbasin Groundwater Sustainability Plan. Retrieved from https://www.napacounty.gov/3218/GSP-Sections#docaccess301ba7a8a4b90269516d7c8f35996882270e684410026520773a52c1f8a47f10 Napa Valley Vintners. (2025). The Economic Impact of Napa County’s Wine and Grape Industry on the Economies of Napa County, California and the US.

National Advisory Council. (2020). Novemeber 2020 Report to the FEMA Administrator.

National Center for Disaster Preparedness. (2020). Vulnerable Populations. Retrieved from https://ncdp.columbia.edu/research/vulnerable-populations/ National Institute of Building Sciences. (2019). Natural Hazard Mitigation Saves: 2019 Report. Retrieved 07 16, 2020, from https://www.nibs.org/page/mitigationsaves National Weather Service. (2020). Education. Retrieved from https://www.weather.gov/ National Weather Service. (2022). Wet Bulb Globe Temperature vs Heat Index. Retrieved March 28, 2022, from Weather.gov: https://www.weather.gov/ict/WBGT
NIBS, 2. (2019, December 1). National Hazard Mitigation Saves: 2019 Report. Retrieved from National Institute of Building Sciences: https://www.nibs.org/projects/natural-hazard-mitigation-saves2019-report NIHHIS. (2021). Extreme Heat - NIHHIS. Retrieved March 7, 2022, from toolkit.climate.gov:
https://toolkit.climate.gov/topics/human-health/extreme-heat Nix, J. (2017, Oct. 25). 42 Dead, 8,400 Structures Burned, More Than $1 Billion in Damage: the Devastating Toll of California’s Wildfires. Retrieved from Mother Jones:
https://www.motherjones.com/environment/2017/10/california-fires-damage-total/ NOAA. (2023). 5 Unexpected Consequances of Extreme Heat. Retrieved from NOAA Research:
https://research.noaa.gov/5-unexpected-consequences-of-extreme-heat/ Prevention, C. f. (n.d.). Climate Change and Extrememe Heat Events.

Sarofim, M., Saha, S., Hawkins, M., Mills, D., Hess, J., Horton, J., . . . St. Julliana, A. (2016). Ch 2: TemperatureRelated Death and Illness. In The Impacts of Climate Change on Human Health in the United States:

A Scientific Assessment (pp. 43-68). Retrieved from
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Shahir Masri et al. (2021). Disproportionate Impacts of Wildfires among Elderly and Low-Income Communities in California from 2000–2020.

Sherwin, B. (2019). After the Storm: The Importance of Acknowledging Environmental Justice in Sustainable Development and Disaster Preparedness.

State of California. (2018). Sacramento Valley Regional Report; California's Forth Climate Change Assessment.

State Water Board. (2018). History of the Water Boards. Retrieved from State Water Resources Control Board: https://www.waterboards.ca.gov/about_us/water_boards_structure/history.html (2017). Strategic Fire Plan Sonoma-Lake-Napa Unit.

Union of Concerned Scientists. (2018). Heat Waves and Climate Change. Retrieved from https://safety.fhwa.dot.gov/ped_bike/tools_solve/fhwasa13037/chap3.cfm US Department of Energy. (2019). Extreme Weather and Climate Vulnerabilities of the Electric Grid.

Retrieved 04 02, 2021, from
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USGS. (2020). Does human activity cause landslides? Retrieved from https://www.usgs.gov/faqs/dohuman-activities-cause-landslides?qt-news_science_products=0#qt-news_science_products Water Education Foundation. (2020). Oroville Dam: Aquapedia Background. Retrieved Jan. 30, 2020, from Aquapedia: https://www.watereducation.org/aquapedia/oroville-dam What is Known About Groundwater. (n.d.). Retrieved from Napa County California:
https://www.countyofnapa.org/1237/What-is-Known-About-Groundwater WWSC. (2023). Post-wildfire sedimentation and release of metals to Conconully Reservoir, Washington. (W.

W. Center, Producer) Retrieved from U.S. Geological Survey:
https://www.usgs.gov/centers/washington-water-science-center/science/post-wildfiresedimentation-and-release-metals CAL OES SUBMITTAL - JUNE 2026
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