City of Rialto
Fire Hazard
Severity Zones
City of Rialto
Fire Hazard
Severity Zones
Background of Fire Hazard Severity Zone Maps
▪ Developed by CalFire and first introduced in 1992 following the 1991 Oakland fire storm
▪ Classifies areas as moderate, high, and very high fire hazard severity zones
▪ Maps were based on vegetation types, topography, fire history, and weather patterns
Purpose of the Maps
▪ Guide local governments in land-use and emergency planning ▪ Required fire prevention programs such as defensible space, fuel modification plans, and construction requirements
City of Rialto
Fire Hazard
Severity Zones
What do the Maps Measure
▪ Fire hazard severity maps evaluate “HAZARD,” not “RISK” ▪ Hazard is based on the physical conditions that create a likelihood and expected fire behavior over a 30 to 50-year period without considering mitigation measures such as home hardening, recent wildfires, fuel reduction efforts.
▪ Risk is the potential damage a fire can do to the area under existing conditions, accounting for any modifications such as fuel reduction projects, defensible space, and ignition resistant building construction.
What new Data is Included in the New Model
▪ Local climate data covering the years 2003-2018
▪ Ember transport (casting) is being modeled based on local distributions of observed wind speed and direction values City of Rialto
Fire Hazard
Severity Zones
Adoption Process Overview
▪ Local maps for Rialto were released on March 24, 2025 ▪ The public review period must be a minimum of 30-days. Rialto made the maps available through social media and the Fire Department website on April 10, 2025, and will continue to solicit questions and concerns from the public.
▪ Local adoption by Ordinance (AB-211) must occur within 120- days of the maps being released which sunsets on July 22, 2025 California Government Code 51175 - 51189
▪ Mandates adoption of the maps
▪ Similarly to the California Fire Code adoption process the City cannot lower the determined fire hazard severity zone but may consider raising it with determined facts & findings
City of Rialto
Fire Hazard
Severity Zones
City of Rialto
Fire Hazard
Severity Zones
Fire Hazard Severity Zones
City of Rialto
Fire Hazard
Severity Zones
Fire Hazard Severity Zone Comparison
2007 Maps 2025 Maps
Moderate High Very High Total
Acreage
City of Rialto
Fire Hazard
Severity Zones
Fire Hazard Severity Zone Key Points
▪ Adoption of maps required by July 22, 2025
▪ Impacts are not retroactive to existing permitted development ▪ The map updates removed the very high fire hazard severity zone from the City of Rialto, However, expanded the high & moderate fire hazard severity zones
▪ California Building Standards Code (Title 24, Part 2, Chapter 7A) applies to new construction in the very high and high fire hazard severity zones but does not apply to the moderate fire hazard severity zone
▪ AB 38 inspections and hazard disclosure required at time of real estate sale in the very high and high fire hazard zones ▪ Insurance impacts are unrelated to map updates however, support mitigation standards that may improve insurability long- term
City of Rialto
Fire Hazard
Severity Zones
Fire Hazard Severity Zone Recommendation
✓ Receive and file the update
✓ Continue coordination with the California State Fire
Marshals office and Planning staff regarding the FHSZ’s ✓ Recommend support for continued public outreach &
education
✓ Prepare to schedule the public hearing and Ordinance
adoption by July 22, 2025
✓ Continue to monitor legislative impacts on Rialto
development based on the fire hazard severity zone
requirements
City of Rialto
Fire Hazard
Severity Zones
Fire Hazard Severity Zone Questions or Concerns
Chris Jensen
Division Chief/Fire Marshal
Rialto Fire Department
Phone (909) 820-2504
Mobile (909) 800-0770
131 S. Willow Ave
Rialto, CA 92376