Photo: CityofSanCarlos · CC BY-SA 4.0More hazard damage per building is expected in San Carlos than in 92% of U.S. towns, mostly from earthquakes
On FEMA’s National Risk Index, San Carlos gets a D for hazard risk: higher expected damage per building than 92% of U.S. towns, #390 of 847 in California. Most of that expected damage is earthquakes (69%), then river and rain flooding (30%). Flood insurance has paid 48 claims here since 1978.
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 stands out about San Carlos’ natural hazards
From FEMA’s model and FEMA’s records, below.
What San Carlos faces
Each hazard’s share of the building damage FEMA expects here, and how its rate compares with the rest of the country.
Earthquakes
River and rain flooding
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 San Carlos’ grade
Earthquakes are 69% of the building damage FEMA expects in San Carlos, and San Carlos’ rate of earthquakes damage is in the top 3% of U.S. census tracts. Next is river and rain flooding at 30% (higher than 67% of U.S. census tracts).
D #390 of 847 in California; higher expected damage per building than 92% of U.S. towns (21,298).
San Carlos’ residents live in 10 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, San Carlos has less expected damage per building than 54% of California towns.
In dollars, FEMA expects about $39.1M a year in losses across San Carlos: $28.3M to buildings, the rest to people and crops.
Does San Carlos flood? Sometimes: 48 flood claims since 1978
Every paid claim on a federal flood insurance policy in San Carlos, from FEMA’s records: 4.1 per 1,000 homes, more than 56% of the 13,809 U.S. towns with a flood insurance record.
- The California Atmospheric River14 claims · $2.1M
- The Pineapple Express - Southern3 claims · $5K
- The Winter storm1 claim · $5K
San Carlos is in FEMA’s Community Rating System (class 9) for its flood-proofing work.
Insurance rates: San Mateo County.5 federal disasters brought FEMA money to San Carlos
Disasters that paid out in San Carlos itself (aid to households or repair grants to the City of San Carlos), newest first, with that year’s flood claims.
- 2023Severe Winter Storms, Straight-line Winds, Flooding, Landslides, and Mudslides$430K to the City of San Carlos for repairs1 flood claim paid that year
- 2022Severe Winter Storms, Flooding, Landslides, and Mudslides99 households applied for aid$548K aid approved$891K to the City of San Carlos for repairs13 flood claims paid that year
- 2020Wildfires36 households applied for aid$500 aid approved
- 2017Severe Winter Storms, Flooding, and Mudslides$23K to the City of San Carlos for repairs1 flood claim paid that year
- 2005Severe Storms, Flooding, Mudslides, and Landslides$20K to the City of San Carlos for repairs1 flood claim paid that year
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 San Carlos after a storm or flood belong in the town’s history. Add one, or share what you remember below.
Add to the San Carlos archive →San Carlos and its neighbors
San Carlos is 2nd of the 3 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 |
| San Carlos | Dmore damage than 92% | earthquakes | 48 |
| Redwood City | Dmore damage than 95% | earthquakes | 62 |
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 San Carlos faces
A short kit for the hazards that drive the building damage here, what to check before you buy, and where neighbors get alerts.
- Drop, cover and hold on.
- Strap tall furniture and the water heater to the wall.
- Know how to shut off the gas.
- 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.
- 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.
- San Carlos residents get 05% off flood insurance.
Know where neighbors sign up for alerts? Add it to the Handbook so everyone has it.
Questions about natural hazards in San Carlos
Is San Carlos at risk for natural disasters?
On FEMA’s National Risk Index, San Carlos has higher expected damage per building than 92% of U.S. towns: D for hazard risk, #390 of 847 in California. Most of the expected damage is earthquakes (69%) and river and rain flooding (30%). This is FEMA’s model of an average year for today’s buildings, not a forecast.
Does San Carlos flood?
Flood insurance has paid 48 claims in San Carlos since 1978, $2.3M in all, or 4.1 per 1,000 homes, more than 56% of U.S. towns with a flood insurance record. 2 properties have flooded more than once. The most claims came from California Atmospheric River (14).
Is San Carlos 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 San Carlos?
San Carlos is in FEMA’s Community Rating System (class 9), which takes 05% off federal flood insurance policies for its flood-proofing work. Premiums depend on the building; policies usually start 30 days after you buy, so get a quote early.
What was the biggest storm in San Carlos?
By FEMA money that reached San Carlos, Severe Winter Storms, Flooding, Landslides, and Mudslides (2022): 99 households applied for aid, $548K approved, and $891K to the City of San Carlos for repairs. By flood claims, California Atmospheric River: 14 paid, $2.1M.
Is San Carlos at risk from earthquakes?
It is the largest share of the building damage FEMA expects here (69%), and San Carlos’ rate for it is in the top 3% of U.S. census tracts.
Storm stories
Memories, warnings and help from neighbors in San Carlos.
Sources: FEMA National Risk Index v1.20 (December 2025), census-tract table, combined by where San Carlos’ 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.