What the state’s fire hazard classifications mean, which laws they trigger, and how to check your property’s designation
Last reviewed: March 2026 · Governing authority: CAL FIRE / Office of the State Fire Marshal · Maps updated: 2025
What FHSZ designations are
Fire Hazard Severity Zones (FHSZ) are geographic classifications assigned by the California Department of Forestry and Fire Protection (CAL FIRE) and the Office of the State Fire Marshal (OSFM) to identify areas where the physical conditions — vegetation, terrain, climate, fire history, and ember spread potential — create an elevated likelihood and expected severity of wildfire. Every property in California can be located on an FHSZ map and assigned one of four classifications: No Designation, Moderate, High, or Very High.
FHSZ designations are hazard classifications — not risk assessments. Hazard describes the underlying physical conditions of an area over a 30 to 50-year planning horizon, without accounting for mitigation measures such as defensible space, home hardening, or fire suppression resources. Risk describes the potential damage a fire can do under current conditions, accounting for those modifications. A property in a Very High FHSZ can have its actual risk reduced through mitigation — but the hazard classification itself remains until the state updates its maps.
FHSZ designations matter because they are the trigger for a wide range of legal obligations — defensible space requirements, home hardening building codes, real estate disclosure requirements, and insurance-related obligations all hinge on whether a property is in a High or Very High FHSZ. Understanding your designation is the starting point for understanding which laws apply to your property.
The fire science behind it
FHSZ maps are built on a science-based, field-tested fire behavior model developed by CAL FIRE. The model evaluates six primary factors: fuel loading (the type, density, and continuity of vegetation), topography (slope steepness and aspect), historical fire occurrence, predicted flame length under extreme weather conditions, ember production and movement (the distance and density of firebrands produced under fire conditions), and typical fire weather patterns including wind speed, humidity, and temperature.
Each of these factors contributes to a hazard score. Areas where the combination of continuous fuel, steep slopes, ember-producing vegetation, and historical Santa Ana or Diablo wind patterns creates a high probability of intense fire behavior receive Very High designations. Areas where those conditions are less severe receive High or Moderate designations.
The distinction between hazard and risk is important for property owners to understand — particularly in relation to insurance. Insurance companies use proprietary risk models that incorporate many of the same underlying data points as FHSZ maps but also factor in structure-specific characteristics, proximity to fire stations, recent fire history, and other variables that change more frequently than the state’s 30-to-50-year hazard model. A property’s FHSZ designation and its insurance risk score are related but not identical. Mitigation work can reduce actual risk even when hazard classification stays the same — and documented mitigation work is what supports an insurance discount claim under the Safer from Wildfires regulation. Learn more at Cal Wildfire Defense.
The four designation levels
No Designation
Properties with no FHSZ designation are in areas where CAL FIRE’s model does not identify elevated fire hazard. In Local Responsibility Areas (LRA), this typically means the property is in a developed urban environment with limited wildland interface. A property with no FHSZ designation may still face wildfire exposure from neighboring areas or from local fire conditions not captured in the model — but it does not trigger the state’s FHSZ-based legal obligations.
Moderate Fire Hazard Severity Zone
Moderate FHSZ areas have a baseline level of fire hazard. In State Responsibility Areas (SRA), moderate designation areas exist but are less common. In LRAs, the 2025 map update — the first comprehensive LRA update since 2007-2011 — has expanded Moderate designations significantly as CAL FIRE’s model now reflects updated climate data, ember spread science, and revised fuel models. Moderate FHSZ designation in an LRA does not currently trigger the same legal obligations as High or Very High — but local governments may adopt stricter standards.
High Fire Hazard Severity Zone
High FHSZ designation triggers significant obligations. In LRAs, High designation was added as a required classification by Senate Bill 63 (2021) — previously only Very High was mapped in LRAs. High FHSZ properties in both SRA and LRA are subject to defensible space requirements under Government Code 51182, AB 38 home hardening disclosure requirements at point of sale, and Civil Code 1102.19 defensible space compliance documentation requirements. Building code requirements under Chapter 7A of the California Building Code apply to new construction and significant renovations in High FHSZ areas in LRAs.
Very High Fire Hazard Severity Zone
Very High FHSZ designation carries the most significant legal obligations and the highest regulatory attention. Properties in Very High FHSZs in both SRA and LRA are subject to the full stack of California wildfire law — PRC 4291 or Government Code 51182 defensible space requirements, AB 38 disclosure, Civil Code 1102.19 compliance documentation, Chapter 7A building codes for new construction, and all insurance-related disclosure and mitigation requirements. Most of San Diego County’s fire-country communities — Alpine, Descanso, Julian, Pine Valley, Fallbrook, Ramona, Warner Springs — carry Very High FHSZ designations in the SRA.
SRA vs. LRA — which map applies to your property
California’s FHSZ maps exist in two parallel systems — one for State Responsibility Areas (SRA) and one for Local Responsibility Areas (LRA). Which map applies to your property depends on your jurisdiction.
In SRAs — rural and semi-rural lands where CAL FIRE has primary financial responsibility for wildfire protection — the FHSZ is set by CAL FIRE and includes Moderate, High, and Very High designations. Most of San Diego County’s unincorporated fire-country communities are in the SRA.
In LRAs — cities, towns, and areas where local fire departments have primary responsibility — FHSZ designations are recommended by the OSFM and then adopted by ordinance by the local agency within 120 days. Local governments can increase the designation level above the state’s recommendation but cannot reduce it. The 2025 LRA map update, released in phases starting February 2025, significantly expanded High and Very High designations in LRAs statewide based on updated fire behavior science.
The 2025 map update
The 2025 LRA FHSZ map update is the most significant revision to California’s fire hazard mapping system since the original LRA maps were released between 2007 and 2011. Released in four phases between February 10 and March 24, 2025, the update reflects new climate data, updated ember spread modeling, revised fuel assessments, and improved fire behavior simulation technology.
The update substantially expanded both High and Very High FHSZ designations in LRAs statewide. Many properties that previously had no FHSZ designation or a Moderate designation now carry High or Very High designations. For those properties, the legal obligations triggered by those designations — defensible space requirements, disclosure obligations, building code standards — now apply.
Local governments received the maps in phases and are required to adopt them by ordinance within 120 days of receipt. Until a local government formally adopts the new maps, the previously adopted maps remain in effect for regulatory purposes — but property owners should check the current OSFM recommendations now, as adoption is occurring statewide throughout 2025.
How to check your property’s designation
The CAL FIRE FHSZ Viewer is the official tool for checking your property’s current fire hazard severity zone designation by address. The viewer is maintained by the Office of the State Fire Marshal and is searchable by address, APN, or map navigation.
The viewer shows both SRA and LRA designations. For LRA properties, the viewer now reflects the 2025 recommended maps. Until a local government adopts its new maps by ordinance, the viewer may show the recommended designation alongside the currently adopted designation — check both.
If you have questions about your property’s designation or believe the map contains an error,
contact the OSFM at FHSZinformation@fire.ca.gov or call 916-633-7655.
What FHSZ designation triggers
Defensible space requirements
Properties in High or Very High FHSZs in the SRA are subject to PRC 4291 — the 100-foot defensible space requirement enforced by CAL FIRE. Properties in High or Very High FHSZs in the LRA are subject to Government Code 51182 or the applicable local vegetation management ordinance. San Diego County has local ordinances that exceed state minimums in many areas — check with your local fire agency for the applicable standard.
Building code requirements
New construction and significant renovation in High and Very High FHSZ areas must comply with Chapter 7A of the California Building Code (CBC) — the Wildland-Urban Interface building standards. Chapter 7A requires fire-resistant roofing, screened vents, ember-resistant construction materials, and other structural features designed to reduce ignition risk. These requirements apply to the structure being built or renovated, not retroactively to existing structures.
Real estate disclosure
FHSZ designation must be disclosed in real estate transactions. Sellers of property in High or Very High FHSZs are required to provide AB 38 home hardening disclosures (for pre-2010 homes) and Civil Code 1102.19 defensible space compliance documentation. Natural Hazard Disclosure (NHD) reports — a standard component of California real estate transactions — include FHSZ designation.
Insurance implications
FHSZ designation is one input into insurer wildfire risk models, but it is not the only one and it does not directly set premiums. CAL FIRE has explicitly noted that FHSZ maps do not affect insurance rates or availability — that is determined by insurers’ proprietary risk models. However, properties in High and Very High FHSZs are more likely to be in areas where insurers apply wildfire risk surcharges or have withdrawn from the market entirely. Understanding both your FHSZ designation and your insurer’s risk score — which you have the right to request under Insurance Code 2644.9 — gives you the full picture.
Official sources
FHSZ designations are governed by California Public Resources Code 4201-4204, California Code of Regulations Title 14 Section 1280, and California Government Code 51175-89.
Related laws
These laws are directly triggered by FHSZ designations or are central to understanding what your designation means.
- PRC 4291 — Defensible space requirement in SRA High and Very High FHSZ
- AB 3074 — Zone 0 ember-resistant zone
- AB 38 — Home hardening disclosure triggered by High or Very High FHSZ
- Civil Code 1102.19 — Defensible space compliance documentation at point of sale
- Insurance Code 2644.9 — Your right to your wildfire risk score
- SRA vs LRA Explained — Which jurisdiction governs your property
Resources and references
The following are official sources used in preparing this page.
- CAL FIRE FHSZ Viewer — Address-searchable designation lookup
- OSFM FHSZ Program — Maps, adoption process, legislation
- PRC 4201-4204 — Statutory authority for FHSZ mapping
- Government Code 51175-89 — LRA FHSZ requirements
- CAL FIRE FHSZ Insurance Q&A — Clarifies that FHSZ maps do not set insurance rates
Disclaimers
The content on this page is provided for educational purposes only and does not constitute legal advice. FHSZ maps are updated periodically — always verify your current designation using the official CAL FIRE FHSZ Viewer and consult with your local fire agency for the adopted designation in your jurisdiction. Last reviewed March 2026.
Fire science content on this site has been developed with the assistance of AI tools and reviewed for accuracy against current CAL FIRE, NFPA, and peer-reviewed fire behavior research. This content is educational and does not constitute legal or professional advice. For property-specific guidance, consult a qualified wildfire mitigation professional.