California
California faces more wildfire risk than any other U.S. state. These resources cover the state-specific regulations, risk maps, and programs that affect California homeowners.
Wildfire Hazard Potential (WHP)
The U.S. Forest Service publishes Wildfire Hazard Potential — a national 270 m raster that quantifies the relative likelihood of wildfire affecting resources and assets. WHP integrates fuels, weather, topography, and historical fire data into five classes: Very Low, Low, Moderate, High, and Very High. Because it covers all 50 states with a consistent methodology, Prefire uses WHP as the baseline risk context for every analysis, including California properties.
USFS WHP dataset ↗CAL FIRE Fire Hazard Severity Zones (FHSZ) — State Regulatory Context
Separate from WHP, CAL FIRE maps California into Moderate, High, and Very High Fire Hazard Severity Zones based on fuel, slope, fire weather, and ember production. Your FHSZ determines which state regulations apply to your property — including vegetation clearance requirements, ember-resistant venting mandates, and disclosure obligations — and affects insurance availability. FHSZ is California-only and not used in Prefire's risk score, but it is important context for CA homeowners navigating compliance.
View the CAL FIRE FHSZ map ↗Public Resources Code § 4291 — The 100-Foot Rule
California's foundational defensible space law requires all structures in or adjacent to a State Responsibility Area to maintain 100 feet of defensible space — or to the property line if it is closer. This covers the two main zones (Zone 1: 5–30 ft, Zone 2: 30–100 ft) and sets requirements for vegetation clearance, ladder fuel removal, and tree spacing. Local fire agencies may enforce stricter standards.
AB 3074 (2021) — The Zone 0 Requirement
Assembly Bill 3074, signed in 2020 and phased in starting in 2023, created a mandatory Zone 0 (0–5 ft) ember-resistant zone immediately around structures. In this zone, all combustible material must be removed: wood mulch, dead vegetation, wood piles, and combustible furniture. Non-combustible hardscaping, concrete, and ember-resistant vents are encouraged. This zone directly addresses the leading cause of home ignition during wildfires.
Read AB 3074 ↗CAL FIRE Resources
Use Prefire for Your California Property
The Prefire analyzer is available for select California communities. Draw your property on the map, answer a short questionnaire, and get a personalized defensible space compliance estimate based on the regulations above.