Photo: Dllu · CC BY-SA 4.0On FEMA’s figures, Mercer Island faces more hazard damage per building than 75% of U.S. towns, mostly from earthquakes
On FEMA’s National Risk Index, Mercer Island gets a C for hazard risk: higher expected damage per building than 75% of U.S. towns, #129 of 285 in Washington. Most of that expected damage is earthquakes (59%), then river and rain flooding (41%). Flood insurance has paid 4 claims here since 2006.
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 Mercer Island faces
Each hazard’s share of the building damage FEMA expects here, and how its rate compares with the rest of the country.
Earthquakes
River and rain flooding
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 Mercer Island’s grade
Earthquakes are 59% of the building damage FEMA expects in Mercer Island, and Mercer Island’s rate of earthquakes damage is in the top 9% of U.S. census tracts. Next is river and rain flooding at 41% (lower than 62% of U.S. census tracts).
C #129 of 285 in Washington; higher expected damage per building than 75% of U.S. towns (21,298).
Mercer Island’s residents live in 6 census tracts; FEMA’s figures are combined by where they live.
The typical Washington town has higher expected damage than 76% of U.S. towns; within the state, Mercer Island has less expected damage per building than 55% of Washington towns.
In dollars, FEMA expects about $18.0M a year in losses across Mercer Island: $13.1M to buildings, the rest to people and crops.
Does Mercer Island flood? Rarely: 4 flood claims since 2006
Every paid claim on a federal flood insurance policy in Mercer Island, from FEMA’s records: 0.4 per 1,000 homes, fewer than 93% of the 13,809 U.S. towns with a flood insurance record.
- The Torrential rain1 claim · $7K
Mercer Island isn’t in FEMA’s Community Rating System, which cuts flood insurance up to 45% in towns that do extra flood-proofing.
Insurance rates: King County.8 federal disasters brought FEMA money to Mercer Island
Disasters that paid out in Mercer Island itself (aid to households or repair grants to the City of Mercer Island), newest first, with that year’s flood claims.
- 2025Severe Storms, Straight-line Winds, Flooding, Landslides, and Mudslides1 households applied for aid$6K aid approved
- 2017Severe Winter Storms, Flooding, Landslides, Mudslides$455K to the City of Mercer Island for repairs
- 2009Severe Winter Storm, Landslides, Mudslides, and Flooding$21K to the City of Mercer Island for repairs
- 2008Severe Winter Storm and Record and Near Record Snow$65K to the City of Mercer Island for repairs
- 2007Severe Storms, Flooding, Landslides, and Mudslides8 households applied for aid$20K aid approved
- 2006Severe Winter Storm, Landslides, and Mudslides$126K to the City of Mercer Island for repairs1 flood claim paid that year
Show all 8
- 2003Severe Storms and Flooding2 households applied for aid$6K aid approved
- 2001Earthquake$7K to the City of Mercer Island for repairs
King County has had 30 natural disasters declared by the President since 1953, most often floods, then severe storms. Not counted: the 2005 Hurricane Katrina evacuee emergency, which covered counties that took in evacuees.
Also 1 FEMA wildfire suppression grant (Fire Management Assistance, not a disaster declaration) for fires in King County, 2022–2022.
Old photos of Mercer Island after a storm or flood belong in the town’s history. Add one, or share what you remember below.
Add to the Mercer Island archive →Mercer Island and its neighbors
Mercer Island is 2nd 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 |
|---|---|---|---|
| Medina | C+more damage than 63% | earthquakes | 1 |
| Mercer Island | Cmore damage than 75% | earthquakes | 4 |
| Seattle | C−more damage than 83% | earthquakes | 156 |
| Bellevue | C−more damage than 83% | earthquakes | 39 |
| Renton | Dmore damage than 89% | earthquakes | 11 |
| Beaux Arts Village | — | 233 residents; we grade 1,000+ | |
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 Mercer Island faces
A short kit for the hazards that drive the building damage here, what to check before you buy, and where neighbors get alerts.
- Drop, cover and hold on.
- Strap tall furniture and the water heater to the wall.
- Know how to shut off the gas.
- 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.
- 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 Mercer Island
Is Mercer Island at risk for natural disasters?
On FEMA’s National Risk Index, Mercer Island has higher expected damage per building than 75% of U.S. towns: C for hazard risk, #129 of 285 in Washington. Most of the expected damage is earthquakes (59%) and river and rain flooding (41%). This is FEMA’s model of an average year for today’s buildings, not a forecast.
Does Mercer Island flood?
Flood insurance has paid 4 claims in Mercer Island since 2006, $123K in all, or 0.4 per 1,000 homes, fewer than 93% of U.S. towns with a flood insurance record. The most claims came from Torrential rain (1).
Is Mercer Island 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 King County, 44% of homes in mapped flood zones carry federal flood insurance, and 0.8% of all homes do.
How much is flood insurance in Mercer Island?
FEMA’s Community Rating System list shows no discount for Mercer Island’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 Mercer Island?
By FEMA money that reached Mercer Island, Severe Winter Storms, Flooding, Landslides, Mudslides (2017): $455K to the City of Mercer Island for repairs. By flood claims, Torrential rain: 1 paid, $7K.
Is Mercer Island at risk from earthquakes?
It is the largest share of the building damage FEMA expects here (59%), and Mercer Island’s rate for it is in the top 9% of U.S. census tracts.
Storm stories
Memories, warnings and help from neighbors in Mercer Island.
Sources: FEMA National Risk Index v1.20 (December 2025), census-tract table, combined by where Mercer Island’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.