Burn Scar Flood Risk — California ZIP Lookup

Burn scar debris flow is a fast-moving slurry of mud, rocks, vegetation, and water that can erupt from drainages downhill of a recent wildfire when intense rainfall hits the burned terrain. Wildfires destroy vegetation that anchors soil, and create hydrophobic ('water-repellent') soil layers that prevent normal absorption. The result: rainwater sheets off the burned slope at high velocity, picking up loose ash, soil, rocks, and burned debris into a flowing mass that can be vastly more destructive than ordinary flooding. The USGS calls these post-fire debris flows the dominant geologic hazard in the 2-5 years following a major Southern California wildfire.

USGS guidance places the primary debris-flow vulnerability window at approximately 2-5 years post-fire, with peak risk during the first 1-2 winter storm seasons. For the January 2025 fires (Eaton, Pacific Palisades, Hurst, Hughes), peak vulnerability runs through approximately 2028-2030. After this window, revegetation typically restores normal hydrology and soil absorption, reducing debris-flow likelihood toward pre-fire baseline. The 2018 Woolsey Fire is now near the end of its primary window, with residual risk diminishing through 2025.

USGS Post-Fire Debris-Flow Hazard Assessments use a 1-year recurrence-interval rainstorm as the design threshold — typically corresponding to a peak 15-minute rainfall intensity of approximately 1.57 inches per hour for Southern California. Atmospheric river events during a strong El Niño can substantially exceed this intensity. Even moderate storm cells that would cause no concern over unburned terrain can initiate debris flows when they hit burn scar drainages above this threshold. The 2018 Montecito debris flow (Thomas Fire burn scar) was triggered by a peak 15-minute rainfall intensity of approximately 0.5 inches per 5 minutes — well within an atmospheric river's normal range.

ZIP-level aggregation is useful for general homeowner planning but is not parcel-specific. The USGS Post-Fire Debris-Flow Hazard Assessments operate at the watershed-basin level: within a single ZIP code, some basins may carry HIGH ratings while others carry LOW ratings depending on slope, drainage area, and burn severity. The 'highest applicable basin rating' methodology used by this tool is conservative — it surfaces the worst-case exposure within the ZIP. For parcel-specific guidance, consult the USGS Post-Fire Debris-Flow Hazard Assessment Viewer linked from this page, or contact LA County Department of Public Works.

Priority actions for HIGH and MODERATE-HIGH burn scar ZIPs: (1) Review NFIP flood insurance status — standard policies have a 30-day waiting period, so purchase by approximately November 1, 2026 to ensure coverage before December atmospheric river peak. (2) Enroll in LA County DPW evacuation alerts and ReadyLA notifications for real-time evacuation orders. (3) Pre-stage sandbags and emergency supplies before forecasted atmospheric river events. (4) Document property condition with photos/video before storm season for insurance claim purposes. (5) Identify an IICRC-certified water damage contractor in advance so emergency response is faster if damage occurs. (6) For active emergency evacuation orders, follow LAFD / local fire department guidance — do NOT shelter in place when an evacuation order has been issued.

If your ZIP is not in this lookup, it means the ZIP is not currently in a documented burn-scar buffer zone for the January 2025 California wildfires (Eaton, Pacific Palisades, Hurst, Hughes) or residual Woolsey Fire 2018 zones. The tool covers Southern California ZIPs with documented USGS Post-Fire Debris-Flow Hazard Assessment exposure to these fires. ZIPs outside these buffer zones do not currently have wildfire-driven elevated debris-flow risk, but standard atmospheric river preparedness still applies for the 2026-27 El Niño season. If new fire events affect your area, check the USGS Post-Fire Debris-Flow Hazard Assessment Viewer for updated hazard assessments.

Yes. Calling (844) 833-1734 is free, and the initial assessment from the matched IICRC-certified contractor is free. You only pay for restoration services you authorize after the assessment.