Sonoma County, CA Fire Regulations: Wildfire Zones (2026)

Sonoma County's wildfire risk is mapped through CAL FIRE's Fire Hazard Severity Zones (FHSZ), which classify land as Moderate, High, or Very High in both the State Responsibility Area (SRA) and Local Responsibility Area (LRA). The County's exposure is severe: the 2017 Tubbs Fire, 2019 Kincade Fire, and 2020 Glass Fire each caused major loss of life and property. Under the updated 2025 CAL FIRE maps, unincorporated Sonoma County added thousands of acres of newly designated Very High fire hazard zone in the LRA, on top of extensive SRA Very High areas.

New structures in a Wildland Urban Interface (WUI) or State Responsibility Area location must comply with ignition-resistant construction standards in 'Chapter 7A, in the California Building Code and Chapter 337 in the California Residential Code,' which require Class A roofing, ember-resistant venting, fire-resistant exterior coverings, windows, decking, and accessory-structure standards. Construction projects and new subdivisions in the SRA and in High or Very High Fire Severity Zones must have a detailed fire protection plan reviewed by Permit Sonoma's Fire Prevention Division before a building permit is issued.

These building requirements work alongside the year-round defensible-space duties in County Code Chapter 13A. Sonoma County notes it does not maintain an official SRA mapping site; property owners can confirm SRA status through CAL FIRE's State Responsibility Area Map Viewer by address.