Photo: Bobak Ha'Eri · CC BY 3.0On FEMA’s figures, Aliso Viejo faces more hazard damage per building than 82% of U.S. towns, mostly from river and rain flooding
On FEMA’s National Risk Index, Aliso Viejo gets a C− for hazard risk: higher expected damage per building than 82% of U.S. towns, #189 of 847 in California. Most of that expected damage is river and rain flooding (68%), then earthquakes (29%). Flood insurance has paid 1 claim here since 2010.
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 Aliso Viejo 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 Aliso Viejo’s grade
River and rain flooding is 68% of the building damage FEMA expects in Aliso Viejo, and Aliso Viejo’s rate of river and rain flooding damage is higher than 82% of U.S. census tracts. Next is earthquakes at 29% (higher than 86% of U.S. census tracts).
C− #189 of 847 in California; higher expected damage per building than 82% of U.S. towns (21,298).
Aliso Viejo’s residents live in 11 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, Aliso Viejo has less expected damage per building than 78% of California towns.
In dollars, FEMA expects about $19.2M a year in losses across Aliso Viejo: $18.3M to buildings, the rest to people and crops.
Does Aliso Viejo flood? Rarely: 1 flood claim since 2010
Every paid claim on a federal flood insurance policy in Aliso Viejo, from FEMA’s records: 0.0 per 1,000 homes, fewer than 100% of the 13,809 U.S. towns with a flood insurance record.
Aliso Viejo 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.3 federal disasters brought FEMA money to Aliso Viejo
Disasters that paid out in Aliso Viejo itself (aid to households or repair grants to the City of Aliso Viejo), newest first, with that year’s flood claims.
- 2017Wildfires40 households applied for aid$1K aid approved
- 2017Severe Winter Storms, Flooding, and Mudslides$9K to the City of Aliso Viejo for repairs
- 2010Severe Winter Storms, Flooding, and Debris and Mud Flows$36K to the City of Aliso Viejo 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 Aliso Viejo after a storm or flood belong in the town’s history. Add one, or share what you remember below.
Add to the Aliso Viejo archive →Aliso Viejo and its neighbors
Aliso Viejo 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 |
|---|---|---|---|
| Laguna Niguel | Cmore damage than 73% | river and rain flooding | 5 |
| Laguna Beach | C−more damage than 77% | earthquakes | 249 |
| Aliso Viejo | C−more damage than 82% | river and rain flooding | 1 |
| Laguna Hills | Dmore damage than 86% | river and rain flooding | 2 |
| Laguna Woods | Dmore damage than 87% | river and rain flooding | 1 |
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 Aliso Viejo 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 Aliso Viejo
Is Aliso Viejo at risk for natural disasters?
On FEMA’s National Risk Index, Aliso Viejo has higher expected damage per building than 82% of U.S. towns: C− for hazard risk, #189 of 847 in California. Most of the expected damage is river and rain flooding (68%) and earthquakes (29%). This is FEMA’s model of an average year for today’s buildings, not a forecast.
Does Aliso Viejo flood?
Flood insurance has paid 1 claim in Aliso Viejo since 2010, $4K in all, or 0.0 per 1,000 homes, fewer than 100% of U.S. towns with a flood insurance record.
Is Aliso Viejo 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 Aliso Viejo?
FEMA’s Community Rating System list shows no discount for Aliso Viejo’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 Aliso Viejo?
By FEMA money that reached Aliso Viejo, Severe Winter Storms, Flooding, and Debris and Mud Flows (2010): $36K to the City of Aliso Viejo for repairs.
Is Aliso Viejo at risk from river and rain flooding?
It is the largest share of the building damage FEMA expects here (68%), and Aliso Viejo’s rate for it is higher than 82% of U.S. census tracts.
Storm stories
Memories, warnings and help from neighbors in Aliso Viejo.
Sources: FEMA National Risk Index v1.20 (December 2025), census-tract table, combined by where Aliso Viejo’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.