Enter any address in San Mateo County, California to see its FEMA flood zone
Flooding in San Mateo County is primarily characterized by standard river and surface water floods, followed by significant flash flood events and occasional coastal flooding. NOAA Storm Events Database records from the last 30 years show 63 flood events, 32 flash flood events resulting in one death, and 6 coastal flood events.
Recent impacts are illustrated by a series of storm systems that struck the Bay Area and Central Coast in December 2025, culminating on Christmas Eve and Christmas Day. These storms disrupted holiday travel, triggered two tornado warnings for the coastal regions of San Mateo and Santa Cruz counties, caused at least 300 flight delays at San Francisco International Airport, and left over 400,000 customers across the Bay Area without power.
Residents in FEMA-designated Zone A should pay the most attention, as this zone accounts for the highest volume of National Flood Insurance Program claims at 535, with an average payout of $29,006 and an average recorded water depth of 4 inches. Property owners in Zone X should also take note, where 211 claims recorded an average water depth of 24 inches and an average payout of $39,197, alongside those in shaded and unshaded Zone X variations and unknown zones.
Summary generated from NOAA storm narratives and NFIP claim data for this county. Not predictive.
52 NOAA storm reports from this county describe what happened, in the words of the meteorologists who were there.
San Mateo County, California has recorded 101 flood-related events since 1996 according to NOAA's Storm Events Database, including 32 flash floods and 63 river or area floods. The county has received 24 federal disaster declarations, 8 of which involved flooding or coastal storms. Enter any address above to check its FEMA flood zone designation.
FEMA Disaster Declarations (1977–2023)
Source: OpenFEMA Disaster Declarations Summaries.
| Declaration | Type | Date |
|---|---|---|
| Severe Winter Storms, Flooding, Landslides, And Mudslides | Flood | Mar 9, 2023 |
| Severe Winter Storms, Straight-line Winds, Flooding, Landslides, And Mudslides | Severe Storm | Feb 21, 2023 |
| Severe Winter Storms, Flooding, And Mudslides | Flood | Jan 8, 2023 |
| Severe Winter Storms, Flooding, Landslides, And Mudslides | Flood | Dec 27, 2022 |
| Czu Lightning Fire Complex | Fire | Aug 20, 2020 |
| Wildfires | Fire | Aug 14, 2020 |
| Covid-19 | Biological | Jan 20, 2020 |
| Covid-19 Pandemic | Biological | Jan 20, 2020 |
| Severe Winter Storms, Flooding, And Mudslides | Flood | Feb 1, 2017 |
| Severe Winter Storms, Flooding, And Mudslides | Flood | Jan 18, 2017 |
NOAA Storm Events Database (1996–2025)
Source: NOAA National Weather Service Storm Events Database.
| Type | Date | Damage |
|---|---|---|
| Flood | Dec 25, 2025 | 0.00K |
| Flood | Dec 24, 2025 | 0.00K |
| Flash Flood | Dec 24, 2025 | 0.00K |
| Flood | Dec 22, 2025 | 0.00K |
| Flood | Nov 17, 2025 | 0.00K |
| Flood | Nov 13, 2025 | 0.00K |
| Flood | Feb 13, 2025 | 0.00K |
| Flood | Feb 4, 2025 | 0.00K |
| Flood | Dec 14, 2024 | 0.00K |
| Flood | Mar 6, 2024 | 0.00K |
Flood — Dec 25, 2025
A series of storm systems impacted the Bay Area and Central Coast from December 19 to 25th, impacting Christmas holiday travel across the region. The most impactful systems arrived on Christmas Eve and Christmas Day. Two tornado warnings were issued for the coastal regions of San Mateo and Santa Cruz counties based off radar indicated rotation. San Francisco International Airport reported delay...
Flood — Dec 24, 2025
A series of storm systems impacted the Bay Area and Central Coast from December 19 to 25th, impacting Christmas holiday travel across the region. The most impactful systems arrived on Christmas Eve and Christmas Day. Two tornado warnings were issued for the coastal regions of San Mateo and Santa Cruz counties based off radar indicated rotation. San Francisco International Airport reported delay...
Flash Flood — Dec 24, 2025
A series of storm systems impacted the Bay Area and Central Coast from December 19 to 25th, impacting Christmas holiday travel across the region. The most impactful systems arrived on Christmas Eve and Christmas Day. Two tornado warnings were issued for the coastal regions of San Mateo and Santa Cruz counties based off radar indicated rotation. San Francisco International Airport reported delay...
Flood — Dec 22, 2025
A series of storm systems impacted the Bay Area and Central Coast from December 19 to 25th, impacting Christmas holiday travel across the region. The most impactful systems arrived on Christmas Eve and Christmas Day. Two tornado warnings were issued for the coastal regions of San Mateo and Santa Cruz counties based off radar indicated rotation. San Francisco International Airport reported delay...
Flood — Nov 17, 2025
A low pressure system brought rain and winds to the Bay Area and Central Coast on November 16 and 17th. Special Marine Warnings and Special Weather Statements were issued due to isolated thunderstorms causing localized heavy rain and gusty winds. The main frontal rain band came through in the overnight hours, with isolated to scattered showers and some thunderstorms continuing into the 17th.
Source: NOAA National Weather Service Storm Events Database.
Source: OpenFEMA NFIP Individual Claims (2.25M records analyzed).
FEMA assigns flood zone designations to areas in San Mateo County, California:
AE High Risk — 1% annual chance of flooding. Insurance required.
VE Very High Risk — Coastal flooding with wave action.
X (Shaded) Moderate Risk — 500-year floodplain.
X Low Risk — Outside major floodplains.
Properties in San Mateo County, California that are in FEMA-designated Special Flood Hazard Areas (zones A and V) with a mortgage from a federally regulated or insured lender, or a federally backed loan, are required to carry flood insurance.
Even outside high-risk zones, flood insurance is recommended. From 2014 to 2024, nearly one-third of NFIP claims came from outside the high-risk Special Flood Hazard Area.
Visit FloodSmart.gov to find an agent and get a quote.