Photo: pelle68 · CC BY-SA 3.0FEMA puts Costa Mesa’s expected hazard damage per building above that of 90% of U.S. towns, mostly from river and rain flooding
On FEMA’s National Risk Index, Costa Mesa gets a D for hazard risk: higher expected damage per building than 90% of U.S. towns, #325 of 847 in California. Most of that expected damage is river and rain flooding (53%), then earthquakes (47%). Flood insurance has paid 67 claims here since 1983.
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 Costa Mesa 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 Costa Mesa’s grade
River and rain flooding is 53% of the building damage FEMA expects in Costa Mesa, and Costa Mesa’s rate of river and rain flooding damage is higher than 84% of U.S. census tracts. Earthquakes add 47%, at a rate in the top 7% of U.S. census tracts.
D #325 of 847 in California; higher expected damage per building than 90% of U.S. towns (21,298).
Costa Mesa’s residents live in 28 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, Costa Mesa has less expected damage per building than 62% of California towns.
Among the 400 U.S. cities of 100,000 or more, Costa Mesa has higher expected damage per building than 84% (#335 of 400). Because it is so big, its total expected yearly loss, $70.1M, is the 170th largest of those 400.
Does Costa Mesa flood? Sometimes: 67 flood claims since 1983
Every paid claim on a federal flood insurance policy in Costa Mesa, from FEMA’s records: 1.5 per 1,000 homes, fewer than 69% of the 13,809 U.S. towns with a flood insurance record.
- The Pineapple Express - Southern12 claims · $84K
Costa Mesa isn’t in FEMA’s Community Rating System, which cuts flood insurance up to 45% in towns that do extra flood-proofing.
Insurance rates: Orange County.2 federal disasters brought FEMA money to Costa Mesa
Disasters that paid out in Costa Mesa itself (aid to households or repair grants to the City of Costa Mesa), newest first, with that year’s flood claims.
- 2017Wildfires60 households applied for aid$1K aid approved
- 2004Severe Storms, Flooding, Debris Flows, and Mudslides10 households applied for aid$394 aid approved$97K to the City of Costa Mesa for repairs1 flood claim paid that year
Orange County has had 27 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 11 FEMA wildfire suppression grants (Fire Management Assistance, not a disaster declaration) for fires in Orange County, 2002–2022.
Old photos of Costa Mesa after a storm or flood belong in the town’s history. Add one, or share what you remember below.
Add to the Costa Mesa archive →Costa Mesa and its neighbors
Costa Mesa is 3rd 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 |
|---|---|---|---|
| Newport Beach | C−more damage than 84% | river and rain flooding | 167 |
| Huntington Beach | Dmore damage than 87% | earthquakes | 490 |
| Costa Mesa | Dmore damage than 90% | river and rain flooding | 67 |
| Santa Ana | Dmore damage than 92% | earthquakes | 184 |
| Irvine | Dmore damage than 92% | river and rain flooding | 29 |
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 Costa Mesa 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 Costa Mesa
Is Costa Mesa at risk for natural disasters?
On FEMA’s National Risk Index, Costa Mesa has higher expected damage per building than 90% of U.S. towns: D for hazard risk, #325 of 847 in California. Most of the expected damage is river and rain flooding (53%) and earthquakes (47%). This is FEMA’s model of an average year for today’s buildings, not a forecast.
Does Costa Mesa flood?
Flood insurance has paid 67 claims in Costa Mesa since 1983, $513K in all, or 1.5 per 1,000 homes, fewer than 69% of U.S. towns with a flood insurance record. 4 properties have flooded more than once. The most claims came from Pineapple Express - Southern (12).
Is Costa Mesa 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 Orange County, 19% of homes in mapped flood zones carry federal flood insurance, and 1.0% of all homes do.
How much is flood insurance in Costa Mesa?
FEMA’s Community Rating System list shows no discount for Costa Mesa’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 Costa Mesa?
By FEMA money that reached Costa Mesa, Severe Storms, Flooding, Debris Flows, and Mudslides (2004): 10 households applied for aid, $394 approved, and $97K to the City of Costa Mesa for repairs. By flood claims, Pineapple Express - Southern: 12 paid, $84K.
Is Costa Mesa at risk from river and rain flooding?
It is the largest share of the building damage FEMA expects here (53%), and Costa Mesa’s rate for it is higher than 84% of U.S. census tracts.
Storm stories
Memories, warnings and help from neighbors in Costa Mesa.
Sources: FEMA National Risk Index v1.20 (December 2025), census-tract table, combined by where Costa Mesa’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.