Wakamiya Inari Shrine · Photo: Joel Bradshaw · Public domainFEMA expects more hazard damage per building in Waipahu than in 98% of U.S. towns, mostly from river and rain flooding
On FEMA’s National Risk Index, Waipahu gets a D− for hazard risk: higher expected damage per building than 98% of U.S. towns, #64 of 93 in Hawaii. Most of that expected damage is river and rain flooding (94%). Flood insurance has paid 1 claim here since 2008.
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 Waipahu 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 Waipahu’s grade
River and rain flooding is 94% of the building damage FEMA expects in Waipahu, and Waipahu’s rate of river and rain flooding damage is in the top 1% of U.S. census tracts. Next is earthquakes at 6% (higher than 81% of U.S. census tracts).
D− #64 of 93 in Hawaii; higher expected damage per building than 98% of U.S. towns (21,298).
Waipahu’s residents live in 11 census tracts; FEMA’s figures are combined by where they live.
The typical Hawaii town has higher expected damage than 96% of U.S. towns; within the state, Waipahu has more expected damage per building than 68% of Hawaii towns.
In dollars, FEMA expects about $20.9M a year in losses across Waipahu: $19.0M to buildings, the rest to people and crops.
Does Waipahu flood? Rarely: 1 flood claim since 2008
Every paid claim on a federal flood insurance policy in Waipahu, from FEMA’s records: 0.1 per 1,000 homes, fewer than 99% of the 13,809 U.S. towns with a flood insurance record.
Waipahu isn’t in FEMA’s Community Rating System, which cuts flood insurance up to 45% in towns that do extra flood-proofing.
Insurance rates: Honolulu County.2 federal disasters brought FEMA money to Waipahu
Disasters that paid out in Waipahu itself (aid to households or repair grants to Waipahu), newest first, with that year’s flood claims.
- 2026Severe Storms, Flooding, Landslides, and Mudslides30 households applied for aid$114K aid approved
- 2008Severe Storms and Flooding22 households applied for aid$65K aid approved1 flood claim paid that year
Honolulu County has had 18 natural disasters declared by the President since 1953, most often severe storms, then floods.
Also 4 FEMA wildfire suppression grants (Fire Management Assistance, not a disaster declaration) for fires in Honolulu County, 2005–2025.
Old photos of Waipahu after a storm or flood belong in the town’s history. Add one, or share what you remember below.
Add to the Waipahu archive →Waipahu and its neighbors
Waipahu 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 |
|---|---|---|---|
| West Loch Estate | Dmore damage than 95% | river and rain flooding | — |
| Waikele | D−more damage than 97% | river and rain flooding | — |
| Waipahu | D−more damage than 98% | river and rain flooding | 1 |
| East Kapolei | D−more damage than 98% | river and rain flooding | — |
| Royal Kunia | D−among the highest damage | river and rain flooding | — |
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 Waipahu 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 Waipahu
Is Waipahu at risk for natural disasters?
On FEMA’s National Risk Index, Waipahu has higher expected damage per building than 98% of U.S. towns: D− for hazard risk, #64 of 93 in Hawaii. Most of the expected damage is river and rain flooding (94%) and earthquakes (6%). This is FEMA’s model of an average year for today’s buildings, not a forecast.
Does Waipahu flood?
Flood insurance has paid 1 claim in Waipahu since 2008, $23K in all, or 0.1 per 1,000 homes, fewer than 99% of U.S. towns with a flood insurance record.
Is Waipahu 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 Honolulu County, 54% of homes in mapped flood zones carry federal flood insurance, and 4.1% of all homes do.
How much is flood insurance in Waipahu?
FEMA’s Community Rating System list shows no discount for Waipahu’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 Waipahu?
By FEMA money that reached Waipahu, Severe Storms, Flooding, Landslides, and Mudslides (2026): 30 households applied for aid, $114K approved.
Is Waipahu at risk from river and rain flooding?
It is the largest share of the building damage FEMA expects here (94%), and Waipahu’s rate for it is in the top 1% of U.S. census tracts.
Storm stories
Memories, warnings and help from neighbors in Waipahu.
Sources: FEMA National Risk Index v1.20 (December 2025), census-tract table, combined by where Waipahu’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.