San Mateo County, CA Fire Regulations: Wildfire Zones (2026)
Key Facts
- Zone classes
- Moderate, High, Very High (CAL FIRE)
- Highest-risk areas
- Santa Cruz Mountains, coastal hills (La Honda, Pescadero)
- Designating law
- Government Code sections 51175-51189
- Defensible space (VHFHSZ)
- 100 ft, PRC 4291 / Gov Code 51182
- WUI building standard
- California Building Code Chapter 7A
- Disclosure
- Natural Hazard Disclosure required at sale
Summary
Unincorporated San Mateo County contains Moderate, High, and Very High Fire Hazard Severity Zones, with the Santa Cruz Mountains and coastal hills (La Honda, Pescadero, and similar) at the highest risk. Mapped zones trigger defensible space (PRC 4291), WUI building standards (CBC Chapter 7A), and real estate disclosure.
What are Fire Hazard Severity Zones? The State Fire Marshal is mandated to classify lands within State Responsibility Areas into Fire Hazard Severity Zones (FHSZ). Fire Hazard Severity Zones fall into one of the following classifications: Moderate High Very High The California laws that require Fire Hazard Severity Zones include California Public Resources Code 4201-4204, California Code of Regulations Title 14, Section 1280 and California Government Code 51175-89.
Frequently Asked Questions FAQ Document (PDF) FAQ Document (PDF) (Spanish) Examples of FHSZ State Minimum Mitigation Requirements Explore Fire Hazard Severity Zones
The Fire Hazard Severity Zone (FHSZ) maps are developed using a science-based and field-tested model that assigns a hazard score based on the factors that influence fire likelihood and fire behavior. Many factors are considered such as fire history, existing and potential fuel (natural vegetation), predicted flame length, blowing embers, terrain, and typical fire weather for the area. There are three levels of hazard in the State Responsibility Areas: moderate, high, and very high.
Full Breakdown
Under California Government Code sections 51175-51189, the State Fire Marshal / CAL FIRE identifies Fire Hazard Severity Zones (FHSZ) in three classes: Moderate, High, and Very High. Zones are split between State Responsibility Areas (SRA), where the state funds wildland fire protection, and Local Responsibility Areas (LRA). Much of rural, unincorporated San Mateo County, including the heavily forested Santa Cruz Mountains and the coastal hills around communities such as La Honda, San Gregorio, and Pescadero, is mapped as high and Very High Fire Hazard Severity Zone and historically prone to frequent wildfire.
The San Mateo County FHSZ map reflects CAL FIRE's final recommendations after local review. Being in a mapped zone carries several regulatory consequences: (1) Defensible space - properties in Very High zones must maintain clearance and wildfire safety practices under Government Code section 51182 and Public Resources Code 4291 (100 feet around structures). (2) WUI building standards - new buildings in High and Very High FHSZ must comply with California Building Code Chapter 7A (Materials and Construction Methods for Exterior Wildfire Exposure): ember-resistant vents, Class A roofs, ignition-resistant exterior walls, and tempered glazing.
(3) Real estate disclosure - sellers must make a natural hazard disclosure of FHSZ status as part of a property transfer. Property owners can check their FHSZ designation through the county's interactive Fire Hazard Severity Zone map tool. Fire protection in the unincorporated area is provided by CAL FIRE / San Mateo County Fire.
Violations & Fines
Failure to maintain defensible space in a Very High FHSZ (PRC 4291 / Gov Code section 51182) can result in notices to abate, re-inspection, and cost-recovery abatement by the fire agency. WUI Chapter 7A non-compliance is a building-permit and certificate-of-occupancy enforcement issue. Failure to provide a Natural Hazard Disclosure of FHSZ status can expose a seller to civil liability in a real estate transaction. Inquiries: San Mateo County Fire Marshal, (650) 573-3846.
Frequently Asked Questions
Is unincorporated San Mateo County in a wildfire hazard zone?
What rules apply if my property is in a Very High zone?
Who provides fire protection in the unincorporated county?
Sources & Official References
Other rules in San Mateo County
California rules heatmap·Compare San Mateo County to another location·View the California fire regulations overview
See something wrong?
Help us keep this page accurate. If you notice an error or outdated information, let us know.