South San Francisco, CA Fire Regulations: Wildfire Zones (2026)

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.