Zane Grey Estate · Photo: Nathan Simmons · CC BY-SA 3.0On FEMA’s figures, Altadena faces more hazard damage per building than 96% of U.S. towns, led by river and rain flooding
On FEMA’s National Risk Index, Altadena gets a D− for hazard risk: higher expected damage per building than 96% of U.S. towns, #596 of 847 in California. Most of that expected damage is river and rain flooding (44%), then earthquakes (35%). Flood insurance has paid 14 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 Altadena 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 Altadena’s grade
River and rain flooding is 44% of the building damage FEMA expects in Altadena, and Altadena’s rate of river and rain flooding damage is higher than 89% of U.S. census tracts. Earthquakes add 35%, at a rate in the top 6% of U.S. census tracts.
D− #596 of 847 in California; higher expected damage per building than 96% of U.S. towns (21,298).
Altadena’s 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, Altadena has more expected damage per building than 70% of California towns.
In dollars, FEMA expects about $35.8M a year in losses across Altadena: $25.6M to buildings, the rest to people and crops.
Does Altadena flood? Sometimes: 14 flood claims since 1978
Every paid claim on a federal flood insurance policy in Altadena, from FEMA’s records: 0.9 per 1,000 homes, fewer than 81% of the 13,809 U.S. towns with a flood insurance record.
- The Pineapple Express - Southern3 claims · $3K
Altadena isn’t in FEMA’s Community Rating System, which cuts flood insurance up to 45% in towns that do extra flood-proofing.
Insurance rates: Los Angeles County.3 federal disasters brought FEMA money to Altadena
Disasters that paid out in Altadena itself (aid to households or repair grants to Altadena), newest first, with that year’s flood claims.
- 2025Wildfires and Straight-line Winds16,234 households applied for aid$77.3M aid approved
- 2020Wildfires28 households applied for aid$14K aid approved
- 2004Severe Storms, Flooding, Debris Flows, and Mudslides276 households applied for aid$154K aid approved
Los Angeles County has had 40 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 44 FEMA wildfire suppression grants (Fire Management Assistance, not a disaster declaration) for fires in Los Angeles County, 2002–2025.
Old photos of Altadena after a storm or flood belong in the town’s history. Add one, or share what you remember below.
Add to the Altadena archive →Altadena and its neighbors
Altadena is 2nd of the 2 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 |
|---|---|---|---|
| Pasadena | Dmore damage than 95% | earthquakes | 31 |
| Altadena | D−more damage than 96% | river and rain flooding | 14 |
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 Altadena 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 Altadena
Is Altadena at risk for natural disasters?
On FEMA’s National Risk Index, Altadena has higher expected damage per building than 96% of U.S. towns: D− for hazard risk, #596 of 847 in California. Most of the expected damage is river and rain flooding (44%) and earthquakes (35%). This is FEMA’s model of an average year for today’s buildings, not a forecast.
Does Altadena flood?
Flood insurance has paid 14 claims in Altadena since 1978, $34K in all, or 0.9 per 1,000 homes, fewer than 81% of U.S. towns with a flood insurance record. The most claims came from Pineapple Express - Southern (3).
Is Altadena 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 Los Angeles County, 33% of homes in mapped flood zones carry federal flood insurance, and 0.5% of all homes do.
How much is flood insurance in Altadena?
FEMA’s Community Rating System list shows no discount for Altadena’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 Altadena?
By FEMA money that reached Altadena, Wildfires and Straight-line Winds (2025): 16,234 households applied for aid, $77.3M approved. By flood claims, Pineapple Express - Southern: 3 paid, $3K.
Is Altadena at risk from river and rain flooding?
It is the largest share of the building damage FEMA expects here (44%), and Altadena’s rate for it is higher than 89% of U.S. census tracts.
Storm stories
Memories, warnings and help from neighbors in Altadena.
Sources: FEMA National Risk Index v1.20 (December 2025), census-tract table, combined by where Altadena’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.