Debris Flow in Sonoma County, California

Debris Flow in Sonoma County, California: 60 recorded events between 2012 and 2025. The strongest on record measured 0. That places the county #1 nationally and #1 statewide for this hazard.

Reporting practice changed over time — early decades are undercounted, not calmer.

The busiest decade for debris flow in Sonoma County is the 2010s, when 58 of the county's 60 recorded events were logged. Comparing decades is useful for spotting active periods, but the earliest years are thin because systematic reporting for this hazard began later.

Within the Sonoma County archive, debris flow makes up 14.3% of all recorded severe weather across 10 hazard types. Nationally the county sits at #1 for this hazard and #1 within California, putting it in the 100.0 percentile of all U.S. counties.

Feb is the peak month for debris flow in Sonoma County with 40 recorded events, while May is the quietest. Seasonality here is a property of the archive as much as the climate: reports cluster where population and spotter networks are densest.

• Flood 255
• Flash Flood 40

How many debris flow events are on record in Sonoma County, California?

60 debris flow events are recorded in Sonoma County between 2012 and 2025, causing 0 direct deaths.

What is the strongest debris flow recorded in Sonoma County?

The strongest debris flow on record in Sonoma County measured 0.

Where does the debris flow data for Sonoma County come from?

All events come from the NOAA/NCEI Storm Events Database, the federal public-domain archive of severe weather reports. Dates are UTC, damage is as reported and not inflation-adjusted, and the most recent entries may still be revised.