Fire Hazard Severity Zone's (FHSZ's) 2025 FAQ's
What is a Fire Hazard Severity Zone?
The State Fire Marshall shall identify areas in the State as Moderate, High, and Very High Hazard Severity Zones based on consistent statewide criteria and the severity of fire hazard that is expected to prevail in those areas. CA GOV 51178
What do Fire Hazard Severity Zones measure?
The maps evaluate “Hazard”, not “Risk”. Hazard is based on physical conditions that create expected fire behavior over a 50-year period without considering short-term modifications. Risk is the potential damage a fire can do to the area under existing conditions, including fuel reductions projects, defensible space, and ignition resistant building construction. osfm.fire.ca.gov/ghsz
What are the key elements of the Fire Hazard Severity Zone Model?
The model has two key elements: probability of an area burning and expected fire behavior under extreme fuel and weather conditions. The factors considered in determining fire hazard within wildland areas in fire history, flame length, terrain, local weather, and potential fuel over a 50-year period. Outside of wildlands, the model considers factors that might lead to buildings being threatened, including terrain, weather, urban vegetation cover, blowing embers, proximity to wildland, fire history, and fire hazard in nearby wildlands. This is not a structure loss model, as key information regarding structure ignition is not included. osfm.fire.ca.gov/fhsz
Why does the model place an emphasis on the spread of embers?
Embers spread wildfire because they can travel long distances in the wind and ignite vegetation, roofs, attics (by getting into vents), and decks. osfm.fire.ca.gov/fhsz
Is there an easy way to determine the Fire Hazard Severity Zone of my property?
You can search by address to find your current designation on the website: osfm.fire.ca.gov/fhsz
Why are Fire Hazard Severity Zones being updated?
The hazard maps are being updated to more accurately reflect the zones in California that are susceptible to wildfire. The process will incorporate new science in local climate data and improved fire assessment modeling in determining hazard ratings. PRC 4125 and GC 51178
Will the new Fire Hazard Severity Zone maps affect my insurance?
Insurance companies use risk models, which differ from hazard models, because they consider susceptibility of a structure to damage from fire and other short-term factors that are not included in hazard modeling. Insurance risk models incorporate additional factors that change more frequently than those that CAL FIRE includes in its hazard mapping, which is built to remain steady. California Department of Insurance
What are the requirements within Fire Hazard Severity Zones?
o Materials and Construction Methods for Exterior Wildfire Exposure CBC Chapter 7A
o Natural hazard real estate disclosure at the time of sale CA CIV 1102.19 (AB 38 2019)
o 100-foot defensible space clearance requirements CA GOV 511882
o Property development standards such as road widths, water supply, and signage CA PRC 4290
o Consideration during future development of Cities and Counties General Plan CA GOV 65302
What is the difference between SRA and LRA?
State Responsibility Area (SRA) is a legal term defining the area where the State has financial responsibility for wildland fire protection and prevention. CA PRC 4102
Local Responsibility Area (LRA) includes incorporated cities, urban regions, agriculture lands, and portions of the desert where the local government is responsible for wildfire protection. CA PRC 4125
When did Fire Hazard Severity Zones begin in Local Responsibility Area?
Assembly Bill 337 (Bates 1992), prompted by the devastating Oakland Hills fire of 1991, calls for CAL FIRE to evaluate fire hazard severity in local responsibility area and to make a recommendation to local jurisdictions where Very High FHSZ exist. CA GOV 51175
How are Fire Hazard Severity Zones determined in Local Responsibility Areas?
CAL FIRE uses an extension of the state responsibility area Fire Hazard Severity Zone model as the basis for evaluating fire hazard in Local Responsibility Area. The Local Responsibility Area hazard rating reflects flame and ember intrusion from adjacent wildlands and from flammable vegetation in urban areas. PRC 4202 and GC 51178
Other Helpful Links
Fire Hazard Severity Zone Viewer -LRA