More hazard damage per building is expected in San Miguel than in 97% of U.S. towns, mostly from river and rain flooding
On FEMA’s National Risk Index, San Miguel gets a D− for hazard risk: higher expected damage per building than 97% of U.S. towns, #655 of 847 in California. Most of that expected damage is river and rain flooding (60%), then earthquakes (40%). Flood insurance has paid 8 claims here since 1980.
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 San Miguel 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 San Miguel’s grade
River and rain flooding is 60% of the building damage FEMA expects in San Miguel, and San Miguel’s rate of river and rain flooding damage is in the top 4% of U.S. census tracts. Earthquakes add 40%, at a rate in the top 5% of U.S. census tracts.
D− #655 of 847 in California; higher expected damage per building than 97% of U.S. towns (21,298).
San Miguel’s residents live in 3 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 Miguel has more expected damage per building than 77% of California towns.
In dollars, FEMA expects about $3.6M a year in losses across San Miguel: $3.2M to buildings, the rest to people and crops.
Does San Miguel flood? Rarely: 8 flood claims since 1980
Every paid claim on a federal flood insurance policy in San Miguel, from FEMA’s records: 6.0 per 1,000 homes, more than 64% of the 13,809 U.S. towns with a flood insurance record.
San Miguel isn’t in FEMA’s Community Rating System, which cuts flood insurance up to 45% in towns that do extra flood-proofing.
Insurance rates: Contra Costa County.2 federal disasters brought FEMA money to San Miguel
Disasters that paid out in San Miguel itself (aid to households or repair grants to San Miguel), newest first, with that year’s flood claims.
- 2022Severe Winter Storms, Flooding, Landslides, and Mudslides21 households applied for aid$32K aid approved
- 2003Earthquake67 households applied for aid$137K aid approved
Contra Costa County has had 17 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.
Old photos of San Miguel after a storm or flood belong in the town’s history. Add one, or share what you remember below.
Add to the San Miguel archive →Get ready for what San Miguel 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 San Miguel
Is San Miguel at risk for natural disasters?
On FEMA’s National Risk Index, San Miguel has higher expected damage per building than 97% of U.S. towns: D− for hazard risk, #655 of 847 in California. Most of the expected damage is river and rain flooding (60%) and earthquakes (40%). This is FEMA’s model of an average year for today’s buildings, not a forecast.
Does San Miguel flood?
Flood insurance has paid 8 claims in San Miguel since 1980, $79K in all, or 6.0 per 1,000 homes, more than 64% of U.S. towns with a flood insurance record.
Is San Miguel 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 Contra Costa County, 28% of homes in mapped flood zones carry federal flood insurance, and 0.9% of all homes do.
How much is flood insurance in San Miguel?
FEMA’s Community Rating System list shows no discount for San Miguel’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 San Miguel?
By FEMA money that reached San Miguel, Earthquake (2003): 67 households applied for aid, $137K approved.
Is San Miguel at risk from river and rain flooding?
It is the largest share of the building damage FEMA expects here (60%), and San Miguel’s rate for it is in the top 4% of U.S. census tracts.
Storm stories
Memories, warnings and help from neighbors in San Miguel.
Sources: FEMA National Risk Index v1.20 (December 2025), census-tract table, combined by where San Miguel’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.