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Fire Hazard Severity Zone Maps in Sonoma, Napa and Marin

By Matthew Martinez, Founder, CEO & Managing Broker, Diamond Real Estate Group. California DRE #01869679.

A Fire Hazard Severity Zone (FHSZ) is the State Fire Marshal’s rating of wildfire hazard on a piece of land: Moderate, High or Very High. To find the zone for a Sonoma, Napa or Marin address, look it up on the Office of the State Fire Marshal’s map viewers, one for State Responsibility Areas and one for Local Responsibility Areas, then confirm with the city or county that adopted the map. The zone matters in a sale because High and Very High designations trigger specific seller disclosures and defensible space documentation, and Very High zones carry extra maintenance duties.

The maps changed recently. The state’s map for State Responsibility Areas took effect on April 1, 2024, and new Local Responsibility Area maps covering cities were released in four phases between February 10 and March 24, 2025. A house that had no zone when it was last sold may have one now. This guide explains how the maps work, how to check a parcel, and what each designation means for buyers and sellers in the North Bay.

What the zones measure

The maps measure hazard, not risk. CAL FIRE’s Office of the State Fire Marshal (OSFM) describes hazard as the physical conditions and expected fire behavior over a 30- to 50-year period, without counting mitigation such as home hardening or fuel reduction. Risk, by contrast, accounts for those changes.

The model weighs fire history, existing and potential fuel, predicted flame length, blowing embers, terrain and typical fire weather. OSFM notes that embers can ignite buildings up to a mile from the main fire, which is one reason zones reach into neighborhoods that don’t look like wildland.

Under Government Code section 51178, the State Fire Marshal identifies Moderate, High and Very High zones using consistent statewide criteria based on fuel loading, slope, fire weather and other factors, including areas where wind is a major cause of wildfire spread.

SRA and LRA: two maps, two sets of rules

Every parcel falls in either a State Responsibility Area (SRA), where the state is financially responsible for wildfire protection, or a Local Responsibility Area (LRA), which covers cities and other land protected by local agencies. Much of the rural hill land in Sonoma, Napa and Marin is SRA. Most incorporated cities are LRA.

	State Responsibility Area (SRA)	Local Responsibility Area (LRA)
Current map	Effective April 1, 2024	Released in four phases, February 10 to March 24, 2025
Zone classes mapped	Moderate, High, Very High	Moderate, High, Very High (earlier LRA maps showed only Very High)
Who adopts it	State, through the Administrative Procedure Act and Office of Administrative Law approval	Each city or county, by ordinance, within 120 days of receiving OSFM’s recommendations
Main defensible space law	Public Resources Code 4291 (all SRA structures)	Government Code 51182 (Very High zones) plus local ordinances

The expansion to all three classes in LRAs comes from SB 63 (Stern, 2021); before it, local agencies were required to adopt only Very High zones. Under Government Code section 51179, a city or county may add areas or raise a zone level, but it cannot lower a zone the State Fire Marshal recommended. It must also post notice of where the map can be viewed at the county recorder, assessor and planning offices.

How to look up a North Bay parcel

Don’t rely on a neighborhood’s reputation or a listing description. Check the specific parcel, because zone lines can split a street.

Start with OSFM. The Fire Hazard Severity Zones page links an SRA viewer and an LRA viewer. Search the address in both, since you may not know which area it is in.
Sonoma County. Permit Sonoma’s FHSZ page posts an interactive map and separate LRA maps for Cloverdale, Cotati, Healdsburg, Petaluma, Rohnert Park, Santa Rosa, Sebastopol, Sonoma, Windsor and the unincorporated county.
Napa County. The county’s 2025 FHSZ page links a map viewer for LRA land and states that the Board of Supervisors will adopt the new maps within 120 days, applying them to unincorporated areas. The county’s real estate inspection page links a separate FHSZ viewer.
Marin County. Marin County Fire’s property lookup tool shows whether a parcel is in a High or Very High zone and routes owners to the right fire agency for an inspection request.
Confirm adoption. Ask the city or county planning or fire office whether it has adopted the 2025 LRA map by ordinance and whether it added any areas. Adoption status varies by jurisdiction.
Compare with the disclosure report. The natural hazard disclosure report in escrow states the zone. If it disagrees with the map you checked, ask the report provider which map edition it used.

For county-level context on these markets, see our guides to Sonoma County, Napa County and Marin County real estate.

What a zone triggers when a home is sold

The designation drives several separate obligations. They don’t all apply to every zone class, which is where buyers and sellers most often get confused.

Requirement	Applies to	Source
Disclosure on the Natural Hazard Disclosure Statement	High or Very High zones, SRA or LRA; separate line for wildland areas	Civil Code 1103.2
Defensible space documentation to the buyer	High or Very High zones	Civil Code 1102.19 (AB 38)
Home hardening disclosure	High or Very High zones, homes built before January 1, 2010	Civil Code 1102.6f
100-foot defensible space and ember-resistant zone	All structures in an SRA	Public Resources Code 4291
100-foot defensible space and ember-resistant zone	Very High zones designated by a local agency	Government Code 51182

The natural hazard disclosure

The statutory form asks whether the property is in a High or Very High zone and whether that zone is in a state or local responsibility area. It tells the buyer that the owner is subject to the maintenance requirements of Government Code 51182.

A separate line covers a wildland area that may contain substantial forest fire risks. That line says the owner is subject to Public Resources Code 4291 and that it is not the state’s responsibility to provide fire protection to structures in the wildlands unless CAL FIRE has a cooperative agreement with a local agency.

Defensible space documentation (AB 38)

Since July 1, 2021, a seller of a home in a High or Very High zone must give the buyer documentation that the property complies with defensible space law or a local vegetation management ordinance. Where no local ordinance requires it, an inspection report from the six months before the sale contract works.

If the seller has no qualifying documentation, the buyer and seller sign a written agreement under which the buyer obtains it, within one year after close of escrow if no local ordinance sets a different rule. Local programs vary. Napa County’s Fire Marshal inspects for free and gives 14 calendar days to fix listed items, and Permit Sonoma runs a fee-based inspection for SRA parcels in High and Very High zones. Our AB 38 inspection guide lists agencies and fees by area.

Home hardening disclosure

For homes built before January 1, 2010 in a High or Very High zone, Civil Code 1102.6f requires a statement that the home was built before the wildland-urban interface building codes took effect, and a disclosure of which of six vulnerable features the seller knows about. These include vents with openings over one-eighth inch, untreated wood shake roofs, combustible materials within five feet of the home, single-pane or non-tempered windows, loose bird stopping or roof flashing, and gutters without noncombustible covers.

Since July 1, 2025, the seller must also give a list of low-cost retrofits and say which of them were completed during the seller’s ownership.

Defensible space and Zone 0

Both Public Resources Code 4291 (SRA) and Government Code 51182 (Very High zones in LRAs) require defensible space of 100 feet from each side of a structure, generally not past the property line, with more intense fuel reduction between 5 and 30 feet. Both also require removing any part of a tree within 10 feet of a chimney outlet and keeping roofs clear of leaves and needles.

Both statutes add an ember-resistant zone within 5 feet of the structure, including any attached deck, to be defined by State Board of Forestry and Fire Protection regulations. Executive Order N-18-25 directed the Board to finish Zone 0 rulemaking by December 31, 2025. As of October 2026, the Board’s page says the rule package is in final review with the Office of Administrative Law, so the final text and compliance dates are not yet in effect. Under PRC 4291, existing structures get three years after the date set for new structures.

CAL FIRE’s Ready for Wildfire guidance already describes Zone 0 practices, such as gravel or pavers instead of bark mulch and noncombustible fencing next to the house. Our article on Zone 0 rules and home sales tracks what to budget for.

Building, remodeling and rebuilding in a zone

California’s wildfire construction standards moved from Chapter 7A of the Building Code into a stand-alone California Wildland-Urban Interface Code, Title 24 Part 7, adopted by the state on February 26, 2025. The 2025 California Building Standards Code, including Part 7, took effect on January 1, 2026.

A house permitted before 2026 may have been reviewed under Chapter 7A, while new work now falls under Part 7. Your local building department decides which standards apply to a given permit, and some agencies add their own rules. Marin County Fire, for example, publishes a standard for remodels and alterations of existing buildings in wildland-urban interface areas.

In a Very High zone, Government Code 51182 also requires an owner building or rebuilding an occupied structure to get a certification from the local building official that the design meets state and local standards, and to obtain the final inspection report. Our home hardening guide covers the upgrades buyers ask about most.

Insurance and the maps

OSFM’s map page links to a California Department of Insurance consumer alert titled “CAL FIRE Hazard Maps Do Not Affect Insurance Rates or Availability.” Insurers use their own wildfire models, so a house outside a mapped zone can still be hard to insure, and the reverse can happen.

The Department of Insurance’s Safer from Wildfires regulation, announced October 17, 2022, requires insurers to recognize mitigation such as upgraded roofs and windows, defensible space and Firewise USA participation in their rates, to give consumers their property’s wildfire risk score, and to offer a right to appeal it.

If traditional coverage isn’t available, the California FAIR Plan’s dwelling policy is a named-peril policy covering fire, lightning, internal explosion and smoke, often paired with a difference-in-conditions policy. See our guides to the FAIR Plan for homebuyers and insurance during escrow. Diamond may refer you to partners we work with; you’re free to choose any provider.

A checklist for buyers and sellers

Look up the parcel on both OSFM viewers and the county or city map, and note SRA or LRA and the zone class.
Sellers in a High or Very High zone: request the defensible space inspection early, before listing, so corrections don’t hold up escrow.
Sellers of pre-2010 homes in those zones: walk the six hardening features with your agent and gather receipts for retrofits you’ve done.
Buyers: get an insurance quote during the contingency period, not after it, and ask the insurer which mitigation discounts it offers.
Buyers planning a remodel or addition: ask the building department which wildfire standards apply before you price the work.
Both sides: read the hazard report alongside the seller’s disclosure package, not separately.

Second-home buyers who won’t be on site often should also plan for year-round vegetation upkeep. Our guide to buying a second home in Sonoma County covers that and other remote-owner issues.

Questions people ask

Is my house in a fire hazard severity zone?

Search the address on the State Fire Marshal’s SRA and LRA map viewers, then check the county or city map. In Sonoma County, Permit Sonoma posts maps for each city and the unincorporated county. The natural hazard disclosure report in escrow also states the zone.

What is the difference between an SRA and an LRA fire zone?

An SRA is land where the state is financially responsible for wildfire protection, and its map took effect April 1, 2024. An LRA is protected by local agencies, mostly cities, and its 2025 map must be adopted by each city or county by ordinance.

Can a city remove my property from a fire zone?

No. Under Government Code 51179, a local agency may add areas or raise a zone level, but it cannot lower a zone the State Fire Marshal recommended.

Does a Moderate zone require an AB 38 inspection?

No. The defensible space documentation rule in Civil Code 1102.19 applies to High and Very High zones. Any home in an SRA, whatever its zone, is still subject to the defensible space law in Public Resources Code 4291, and some local fire agencies, such as Central Marin Fire and Ross Valley Fire, require their own resale inspection regardless of the state zone.

Will being in a Very High zone raise my insurance premium?

A Department of Insurance consumer alert, linked from the State Fire Marshal’s map page, says the maps don’t affect insurance rates or availability. Insurers use their own risk models, so get a quote for the specific house before you remove your contingencies.

Are Zone 0 rules in effect yet?

Not as of October 2026. The Board of Forestry’s page says the Zone 0 rule package is in final review with the Office of Administrative Law. Once it takes effect, existing homes get three years after the date set for new construction.

Do fire zone rules apply in Lake and Mendocino counties too?

Yes. The state laws described here apply statewide, and the same OSFM viewers cover every county. Local inspection programs and ordinances differ, so check with the county or fire district.

If you’re buying or selling a home in a mapped zone and want help lining up the inspection, disclosures and insurance timing, contact Diamond Real Estate Group, or start with our home buying process guide. This is general information, not legal advice; talk to a California real estate attorney about your situation.

Sources & notes

Last reviewed October 2026 by Matthew Martinez.