568 flood insurance claims·$4.6M paid·8 federal flood & hurricane disasters
Share of the whole county outline, rivers and lakes included; parts FEMA hasn’t mapped count as zero.
Shaded areas are FEMA’s mapped flood hazard zones in and around Alameda County, California. Zoomed out they are simplified; at street level the map switches to FEMA’s exact layer. Tap anywhere to check that spot, or search an address above.
Flooding from standard flood events dominates Alameda County, accounting for 148 recorded events and 1 death over the last 30 years, alongside 27 flash flood events and 3 coastal flood events.
Recent impacts are illustrated by a series of storm systems that impacted the Bay Area and Central Coast from December 19 to December 25, 2025, disrupting Christmas holiday travel with flight delays at San Francisco International Airport and widespread power outages.
Property owners and residents should examine their specific FEMA flood zones, as historical NFIP claims vary significantly by designation. Zone A recorded 177 claims with an average payout of $16,634 and an average recorded water depth of 13 inches. Zone X recorded 120 claims with an average payout of $30,215 and an average recorded water depth of 35 inches. Zone X_UNSHADED logged 107 claims with an average payout of $7,020 and an average recorded water depth of 3 inches, while Zone X_SHADED recorded 36 claims averaging $22,892 in payouts with an average water depth of 2 inches. Properties with unknown zones recorded 128 claims averaging a $3,450 payout and an average water depth of 2 inches.
Summary written from NOAA storm reports and NFIP claims for this county. Not a prediction.
45% of Alameda County’s flood insurance claims were on properties rated outside FEMA’s high-risk zones.
320 NFIP claims with a recorded rated flood zone, 1978 to date. The zone is the one FEMA used to rate that policy, which may not match today’s map. Source: OpenFEMA NFIP claims.
In flood insurance claims here that reported a flood depth, the average was 11 inches.
Drawn to scale against an 80-inch door. Even a few inches soaks flooring, the bottom of the drywall and anything plugged in near the floor.
Average of the depths reported on claims (zero and implausible values left out); FEMA’s record doesn’t say exactly where each depth was measured. Source: OpenFEMA NFIP claims.
The worst year was 1998, with 103 claims and $1.1M paid, the year of Severe Winter Storms and Flooding.
Bar height is scaled by square root so ordinary years stay visible next to the worst one. NFIP claims by year of loss. Source: OpenFEMA.
86 NOAA storm reports from Alameda County describe what happened, in the words of the forecasters who covered it. Read the California flood stories →
24 federal disaster declarations since 1970, 8 of them floods, coastal storms or hurricanes.
| Disaster | Began |
|---|---|
| Severe Winter Storms, Straight-line Winds, Flooding, Landslides, And Mudslides | Feb 21, 2023 |
| Severe Winter Storms, Flooding, And Mudslides | Jan 8, 2023 |
| Severe Winter Storms, Flooding, Landslides, And Mudslides | Dec 27, 2022 |
| Severe Winter Storms, Flooding, And Mudslides | Feb 1, 2017 |
| Severe Winter Storms, Flooding, And Mudslides | Jan 18, 2017 |
| Severe Storms, Flooding, Landslides, And Mudslides | Mar 29, 2006 |
| Severe Storms, Flooding, Mudslides, And Landslides | Dec 17, 2005 |
| Hurricane Katrina Evacuation | Aug 29, 2005 |
Weather and water disasters only; most recent first. Source: OpenFEMA Disaster Declarations.
178 since 1996: 27 flash floods, 148 river or area floods and 3 coastal floods or surges.
| Event | Date | Damage |
|---|---|---|
| Flash Flood | Dec 25, 2025 | — |
| Flood | Dec 24, 2025 | — |
| Flood | Dec 22, 2025 | — |
| Flood | Nov 17, 2025 | — |
| Flood | Nov 13, 2025 | — |
| Flood | Feb 13, 2025 | — |
| Flood | Feb 4, 2025 | — |
| Flood | Jan 31, 2024 | — |
— = no damage estimate in the record. Source: NOAA Storm Events Database.
Flash 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 delays of at least 300 fl…
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 delays of at least 300 fl…
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 delays of at least 300 fl…
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.
National Weather Service narratives, lightly trimmed. Source: NOAA Storm Events Database.
Every colour on the map above is a place on this drawing: where the ground sits relative to the flood FEMA plans for.
If a building in Alameda County is in a high-risk zone (A or V) and its mortgage comes from a federally regulated or insured lender, or is federally backed, flood insurance is required.
Outside those zones it is optional, and often worth having: from 2014 to 2024 nearly one-third of NFIP claims came from outside the high-risk Special Flood Hazard Area. Since Risk Rating 2.0, NFIP premiums are set for each building, so the only reliable price is a quote: FloodSmart.gov or a local agent.