Photo: Pi.1415926535 · CC BY-SA 3.0FEMA expects more hazard damage per building in Foster City than in 97% of U.S. towns, mostly from river and rain flooding
On FEMA’s National Risk Index, Foster City gets a D− for hazard risk: higher expected damage per building than 97% of U.S. towns, #661 of 847 in California. Most of that expected damage is river and rain flooding (64%), then earthquakes (35%). Flood insurance has paid 10 claims here since 1998.
Graded on FEMA’s expected yearly building damage per dollar of building value (NRI v1.20, December 2025), weighted by where residents live; flood claims are shown, not graded. How hazard risk is graded
What Foster City faces
Each hazard’s share of the building damage FEMA expects here, and how its rate compares with the rest of the country.
River and rain flooding
Earthquakes
Shares are of FEMA’s expected building damage, the measure the grade uses; ranks compare each hazard’s building-damage rate with all 85,154 U.S. census tracts. In FEMA’s terms, river and rain flooding is FEMA’s “Inland Flooding” (rivers and streams overflowing their banks, or rain overwhelming drainage). FEMA defines coastal flooding as high or rising tides and storm surge, so surge damage is counted there. Drought isn’t listed: FEMA counts its losses in crops only.
What’s behind Foster City’s grade
River and rain flooding is 64% of the building damage FEMA expects in Foster City, and Foster City’s rate of river and rain flooding damage is in the top 3% of U.S. census tracts. Earthquakes add 35%, at a rate in the top 7% of U.S. census tracts.
D− #661 of 847 in California; higher expected damage per building than 97% of U.S. towns (21,298).
Foster City’s residents live in 9 census tracts; FEMA’s figures are combined by where they live.
The typical California town has higher expected damage than 92% of U.S. towns; within the state, Foster City has more expected damage per building than 78% of California towns.
In dollars, FEMA expects about $35.5M a year in losses across Foster City: $31.9M to buildings, the rest to people and crops.
Does Foster City flood? Sometimes: 10 flood claims since 1998
Every paid claim on a federal flood insurance policy in Foster City, from FEMA’s records: 0.7 per 1,000 homes, fewer than 84% of the 13,809 U.S. towns with a flood insurance record.
- The Pineapple Express - Southern2 claims · $10K
- The California Atmospheric River2 claims · $107K
- The Winter storm1 claim · $15K
Foster City isn’t in FEMA’s Community Rating System, which cuts flood insurance up to 45% in towns that do extra flood-proofing.
Insurance rates: San Mateo County.2 federal disasters brought FEMA money to Foster City
Disasters that paid out in Foster City itself (aid to households or repair grants to the City of Foster City), newest first, with that year’s flood claims.
- 2022Severe Winter Storms, Flooding, Landslides, and Mudslides18 households applied for aid$68K aid approved2 flood claims paid that year
- 2020Wildfires14 households applied for aid$500 aid approved
San Mateo County has had 19 natural disasters declared by the President since 1953, most often severe storms, then floods. Not counted: the 2005 Hurricane Katrina evacuee emergency, which covered counties that took in evacuees.
Also 2 FEMA wildfire suppression grants (Fire Management Assistance, not a disaster declaration) for fires in San Mateo County, 2010–2020.
Old photos of Foster City after a storm or flood belong in the town’s history. Add one, or share what you remember below.
Add to the Foster City archive →Foster City and its neighbors
Foster City is 5th of the 5 graded towns here, from least expected damage per building to most. Tap a town to see its hazards.
| Town | Hazard risk | Mostly (buildings) | Flood claims |
|---|---|---|---|
| Belmont | Dmore damage than 91% | earthquakes | 12 |
| Redwood City | Dmore damage than 95% | earthquakes | 62 |
| Hayward | Dmore damage than 95% | earthquakes | 16 |
| San Mateo | D−more damage than 95% | earthquakes | 49 |
| Foster City | D−more damage than 97% | river and rain flooding | 10 |
Hazard risk = FEMA’s expected yearly building damage per dollar of building value, vs. the 21,298 U.S. towns we grade; the map is shaded by fifths of the same scale. Flood claims = paid federal flood insurance claims on record.
Get ready for what Foster City faces
A short kit for the hazards that drive the building damage here, what to check before you buy, and where neighbors get alerts.
- Turn around at flooded roads: a foot of moving water can carry off a car.
- Flood insurance usually takes 30 days to start, so buy it before the forecast.
- Keep papers and medicines up high, in a grab-and-go bag.
- Drop, cover and hold on.
- Strap tall furniture and the water heater to the wall.
- Know how to shut off the gas.
- Look up the address on FEMA’s flood map.
- Ask the seller or landlord whether it has ever flooded, and what flood insurance costs there.
- Get a flood insurance quote early: policies usually start 30 days after you buy.
Know where neighbors sign up for alerts? Add it to the Handbook so everyone has it.
Questions about natural hazards in Foster City
Is Foster City at risk for natural disasters?
On FEMA’s National Risk Index, Foster City has higher expected damage per building than 97% of U.S. towns: D− for hazard risk, #661 of 847 in California. Most of the expected damage is river and rain flooding (64%) and earthquakes (35%). This is FEMA’s model of an average year for today’s buildings, not a forecast.
Does Foster City flood?
Flood insurance has paid 10 claims in Foster City since 1998, $210K in all, or 0.7 per 1,000 homes, fewer than 84% of U.S. towns with a flood insurance record. 2 properties have flooded more than once. The most claims came from Pineapple Express - Southern (2).
Is Foster City in a flood zone?
Flood zones are drawn street by street, so the answer depends on the address: look it up on FEMA’s flood map. In San Mateo County, 31% of homes in mapped flood zones carry federal flood insurance, and 1.8% of all homes do.
How much is flood insurance in Foster City?
FEMA’s Community Rating System list shows no discount for Foster City’s flood program. Premiums depend on the building; policies usually start 30 days after you buy, so get a quote early.
What was the biggest storm in Foster City?
By FEMA money that reached Foster City, Severe Winter Storms, Flooding, Landslides, and Mudslides (2022): 18 households applied for aid, $68K approved. By flood claims, Pineapple Express - Southern: 2 paid, $10K.
Is Foster City at risk from river and rain flooding?
It is the largest share of the building damage FEMA expects here (64%), and Foster City’s rate for it is in the top 3% of U.S. census tracts.
Storm stories
Memories, warnings and help from neighbors in Foster City.
Sources: FEMA National Risk Index v1.20 (December 2025), census-tract table, combined by where Foster City’s residents lived in the 2020 census; OpenFEMA: NFIP redacted claims, multiple-loss properties, community status book and residential penetration rates, housing assistance (owners and renters), public assistance funded projects, hazard mitigation properties and disaster declarations. Homes: Census ACS 2020–24. Preparedness tips: Ready.gov. FEMA’s model is an average of expected damage, not a forecast. How hazard risk is graded.