64
Recorded events
0
Direct deaths
0
Direct injuries
$10.1M
Property damage
Flood in San Mateo County, California: 64 recorded events between 1996 and 2026. The strongest on record measured 0. That places the county #165 nationally and #21 statewide for this hazard.
Decade by decade
Flood in San Mateo County, California: events per decade
Reporting practice changed over time — early decades are undercounted, not calmer.
The busiest decade for flood in San Mateo County is the 2010s, when 31 of the county's 64 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 San Mateo County archive, flood makes up 39.3% of all recorded severe weather across 8 hazard types. Nationally the county sits at #165 for this hazard and #21 within California, putting it in the 94.3 percentile of all U.S. counties.
Seasonality
Events by month
Jan is the peak month for flood in San Mateo County with 19 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.
Most recent
Latest recorded events
| Date | Location | Magnitude | Damage |
|---|---|---|---|
| Jan 5, 2026 | BURLINGAME | — | $0 |
| Dec 25, 2025 | HILLSBOROUGH | 0 | $0 |
| Dec 25, 2025 | EDGEMAR | 0 | $0 |
| Dec 24, 2025 | WOODSIDE | 0 | $0 |
| Dec 22, 2025 | DALY CITY | 0 | $0 |
| Dec 22, 2025 | STERLING PARK | 0 | $0 |
| Nov 17, 2025 | SAN BRUNO | 0 | $0 |
| Nov 17, 2025 | COLMA | 0 | $0 |
| Nov 17, 2025 | (SQL)SAN CARLOS ARPT | 0 | $0 |
| Nov 13, 2025 | TANFORAN | 0 | $0 |
From the record
What the reports say
Written by National Weather Service staff at the time of the event · public domain
Heavy rain caused Harbor Boulevard at the underpass of State Route 82 to flood submerging a car to the base of its windows. The road was barricaded to stop anyone else from driving into the water. Also in Belmont, a car repair business evacuated its building as 3 inches of water covered the floor. Belmont Creek was to blame.
Heavy rain caused Pulgas Creek to overflow its banks and flood some classrooms at Central Middle School in San Carlos. Also, several streets were blocked off in low-lying areas just west of US Highway 101, including Taylor Avenue in San Carlos and parts of Rolison Road in Redwood City. In Atherton, officials closed March Road from Middlefield Road to Fair Oaks Avenue because a creek had begun to flood.
CHP reported flash flooding of US Highway 101 at Oyster Point Road in South San Francisco at 5:58 AM. By 10:58 AM, the entire roadway had flooded and the highway was closed. The flooding caused traffic backups and diversions with Interstate 280 as the alternate. The northbound lanes were reopened around 8 PM and the southbound lanes around 9 PM.
Quick answers
Frequently asked
How many flood events are on record in San Mateo County, California?
64 flood events are recorded in San Mateo County between 1996 and 2026, causing 0 direct deaths.
What is the strongest flood recorded in San Mateo County?
The strongest flood on record in San Mateo County measured 0.
Where does the flood data for San Mateo 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.
Cite this page
“Flood in San Mateo County, California.” Severe Weather History. severeweatherhistory.com/county/california/san-mateo-county/flood/ · Data: NOAA/NCEI, FEMA, U.S. Census — public domain.