On FEMA’s figures, Diablo faces more hazard damage per building than 94% of U.S. towns, led by river and rain flooding
On FEMA’s National Risk Index, Diablo gets a D for hazard risk: higher expected damage per building than 94% of U.S. towns. Most of that expected damage is river and rain flooding (44%), then earthquakes (43%). Flood insurance has paid 1 claim here since 2017.
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 Diablo 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
Wildfire
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 Diablo’s grade
River and rain flooding is 44% of the building damage FEMA expects in Diablo, and Diablo’s rate of river and rain flooding damage is higher than 85% of U.S. census tracts. Earthquakes add 43%, at a rate in the top 6% of U.S. census tracts.
D higher expected damage per building than 94% of U.S. towns (21,298).
Diablo’s residents live in 2 census tracts; FEMA’s figures are combined by where they live.
In dollars, FEMA expects about $1.1M a year in losses across Diablo: $1.0M to buildings, the rest to people and crops.
Does Diablo flood? Rarely: 1 flood claim since 2017
Every paid claim on a federal flood insurance policy in Diablo, from FEMA’s records: 2.1 per 1,000 homes, fewer than 60% of the 13,809 U.S. towns with a flood insurance record.
Diablo 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.1 federal disaster brought FEMA money to Diablo
Disasters that paid out in Diablo itself (aid to households or repair grants to Diablo), newest first, with that year’s flood claims.
- 2022Severe Winter Storms, Flooding, Landslides, and Mudslides19 households applied for aid$60K 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 Diablo after a storm or flood belong in the town’s history. Add one, or share what you remember below.
Add to the Diablo archive →Diablo and its neighbors
Diablo has the lowest expected damage per building of the 4 graded towns here. Tap a town to see its hazards.
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 Diablo 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.
- Clear dead leaves and brush within 5 feet of the house.
- Sign up for local alerts and know two ways out.
- Keep N95 masks for smoky days.
- 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 Diablo
Is Diablo at risk for natural disasters?
On FEMA’s National Risk Index, Diablo has higher expected damage per building than 94% of U.S. towns: D for hazard risk. Most of the expected damage is river and rain flooding (44%) and earthquakes (43%). This is FEMA’s model of an average year for today’s buildings, not a forecast.
Does Diablo flood?
Flood insurance has paid 1 claim in Diablo since 2017, $10K in all, or 2.1 per 1,000 homes, fewer than 60% of U.S. towns with a flood insurance record.
Is Diablo 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 Diablo?
FEMA’s Community Rating System list shows no discount for Diablo’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 Diablo?
By FEMA money that reached Diablo, Severe Winter Storms, Flooding, Landslides, and Mudslides (2022): 19 households applied for aid, $60K approved.
Is Diablo at risk from river and rain flooding?
It is the largest share of the building damage FEMA expects here (44%), and Diablo’s rate for it is higher than 85% of U.S. census tracts.
Storm stories
Memories, warnings and help from neighbors in Diablo.
Sources: FEMA National Risk Index v1.20 (December 2025), census-tract table, combined by where Diablo’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.