Much of unincorporated Orange County - especially the Silverado, Modjeska, and Trabuco canyon communities - lies in CAL FIRE-designated Very High, High, or Moderate Fire Hazard Severity Zones. CAL FIRE released an updated FHSZ map for OC's unincorporated areas in 2025. Properties in these zones face stricter defensible-space, building, and disclosure requirements.
CAL FIRE (the California Department of Forestry and Fire Protection) classifies land by wildfire risk into Moderate, High, and Very High Fire Hazard Severity Zones (FHSZ). CAL FIRE released an updated Fire Hazard Severity Zone map for the unincorporated areas of Orange County in 2025, using the latest climate data, fire history, topography, and wildfire modeling. The canyon communities of Silverado, Williams Canyon, Modjeska, and Trabuco - all served by OCFA - sit in mapped fire-hazard zones, and the 2020 Bond Fire burned through this area, underscoring the risk. Buildings and properties in higher FHSZs face more stringent requirements for both building construction (wildland-urban interface materials) and vegetation maintenance. Owners in High and Very High zones must maintain defensible space under Public Resources Code 4291 (clearance up to 100 feet), and on sale of such property a Defensible Space Disclosure is required under California Civil Code 1102.19. OC Public Works and OC Development Services publish the Very High Fire Hazard Severity Zone map used to apply these building and vegetation rules, and OCFA provides an interactive tool for residents to find their FHSZ designation and request defensible-space inspections.
Wildfire-zone rules are enforced through building-permit review (stricter construction standards in higher zones), defensible-space inspections by OCFA, and disclosure requirements at sale. Failure to maintain PRC 4291 defensible space in a designated zone can lead to abatement notices and citations; a seller who cannot provide a compliant Defensible Space Disclosure (Civ. Code 1102.19) may be unable to close escrow.
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Side-by-side rule comparisons with other cities in Orange County.
See how other cities in Orange County handle wildfire zones.
See how Costa Mesa's wildfire zones rules stack up against other locations.
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