NHC HURDAT2 · SPC Tornado Database
Hurricanes and Tornadoes That Hit Mercer Island, WA
Every tropical system within 75 miles since 1851 and every tornado within 25 miles since 1950.
Data: NOAA NHC HURDAT2 and NOAA SPC tornado and hail reports, through 2025 · Updated
No tropical storm or hurricane has passed within 75 miles of Mercer Island, Washington since records began in 1851. Since 1950, 10 tornadoes have touched down within 25 miles, 1 of them rated EF3 or stronger.
- Hurricanes
- 0
- Tropical storms
- 0
- Tornadoes
- 10
- EF3 or stronger
- 1
within 75 mi, since 1851
below hurricane strength
within 25 mi, since 1950
no recorded deaths
What the records show for Mercer Island
The strongest of the 10 tornadoes within 25 miles was an F3 on December 12, 1969; its path came within 5 miles. Of the 10, 2 had paths within 5 miles of the city centre, and 3 have come since 2000. December has had the most tornadoes, 3. The most recent tornado was on December 18, 2018. Mercer Island has more tornadoes within 25 miles than 69% of the 226 Washington cities on this site. Hail has been reported within 10 miles 2 times since 1972, with stones up to 1.5 inches (ping pong ball size). Mercer Island has more hail reports within 10 miles than 60% of the 226 Washington cities.
Compare Mercer Island's storm record with another city →
Tornadoes within 25 miles of Mercer Island
By decade
- 2010s2
- 2000s1
- 1990s3
- 1970s1
- 1960s3(1 EF3+)
| Date | Rating | Distance | Path | Killed / injured |
|---|---|---|---|---|
| Dec 12, 1969 | F3 | 5 mi | 3.8 mi | 0 / 1 |
| Dec 18, 2018 | EF2 | 18 mi | 1.35 mi | 0 / 0 |
| Jan 18, 2015 | EF1 | 23 mi | 4.1 mi | 0 / 0 |
| Dec 22, 1971 | F1 | 13 mi | 0.5 mi | 0 / 0 |
| Sep 28, 1962 | F1 | 4 mi | 0.1 mi | 0 / 0 |
| Jun 11, 2001 | F0 | 14 mi | — | 0 / 0 |
| Aug 24, 1997 | F0 | 25 mi | 0.5 mi | 0 / 0 |
| Jun 23, 1996 | F0 | 22 mi | 0.4 mi | 0 / 0 |
| Apr 9, 1991 | F0 | 20 mi | 0.8 mi | 0 / 0 |
| Aug 18, 1964 | F0 | 8 mi | 5.2 mi | 0 / 0 |
The strongest 10 of 10, by rating and then by deaths. Ratings before February 2007 are on the original Fujita scale.
Hail in Mercer Island
The Storm Prediction Center has 2 hail reports within 10 miles of Mercer Island since 1972. All were 1 inch across or larger, and none reached 2 inches. The largest, 1.5 inches (ping pong ball size), fell on June 8, 1972. The most recent report is from March 10, 2006.
Source: NOAA Storm Prediction Center severe weather reports, data through 2025.
Weather by month in Mercer Island
The nearest NOAA station with 1991–2020 climate normals is Seattle Boeing Field, WA, 4 miles southwest of Mercer Island at 20 feet. August is the warmest, with an average high of 77°F and low of 58°F; December is the coolest, at 48°F and 36°F. November is the wettest at 5.8 inches of precipitation on average and July the driest at 0.6 inches; the year adds up to 36.5 inches over 86 days with at least a tenth of an inch. Highs reach 90°F on about 3 days a year, almost all from July to August. Lows fall below freezing on about 30 nights a year. That 36.5 inches is more than at 45 of the 86 Washington stations used on this site (52%). Medina, 4 miles north, has its own station (Seattle Sand Pt Wsfo, WA): 38.0 inches a year, 1.5 more than here, and the same August average high, 77°F.
Water temperature at the NOAA tide station Tacoma, WA, 23 miles south, averaged 56°F in September and 48°F in March over 2021–2025. No month averaged 80°F. Sea level at the Seattle tide gauge, 6 miles from Mercer Island, has risen 0.82 ± 0.03 inches per decade from 1899 to 2025, NOAA's linear trend; at that pace it is 8.2 inches in a hundred years. That is faster than at 42 of the 144 U.S. gauges with a NOAA trend.
| Month | High °F | Low °F | Precip. in | Days ≥ 0.1" | Water °F |
|---|---|---|---|---|---|
| Jan | 49 | 37 | 5.2 | 12 | 49 |
| Feb | 51 | 37 | 3.7 | 9 | 48 |
| Mar | 55 | 39 | 3.9 | 11 | 48 |
| Apr | 60 | 44 | 2.9 | 8 | 49 |
| May | 67 | 49 | 2.0 | 6 | 51 |
| Jun | 71 | 54 | 1.2 | 4 | 53 |
| Jul | 77 | 58 | 0.6 | 1 | 55 |
| Aug | 77 | 58 | 0.8 | 2 | 56 |
| Sep | 72 | 54 | 1.4 | 4 | 56 |
| Oct | 61 | 46 | 3.5 | 8 | 55 |
| Nov | 53 | 40 | 5.8 | 11 | 53 |
| Dec | 48 | 36 | 5.5 | 11 | 51 |
| Year | 62 | 46 | 36.5 | 86 | 52 |
Averages for 1991–2020 at Seattle Boeing Field, WA (20 ft), from NOAA NCEI U.S. Climate Normals; water temperature: average of hourly readings 2021–2025 at the NOAA tide station Tacoma, WA, from NOAA Tides & Currents. Normals describe the station; the farther a place is from it, and the bigger the difference in height, the more its weather can differ.
Floods, thunderstorm wind and lightning near Mercer Island
Since 1996, the National Weather Service has logged 13 flood, rain, thunderstorm wind and lightning events that began within 10 miles of Mercer Island: 7 heavy rain events, 4 lightning strikes, 1 flash flood and 1 thunderstorm wind report. They killed 2 people and injured 2, and the NWS estimated $3.3 million in property and crop damage. The strongest thunderstorm gust on record here was 62 mph, on December 14, 2010.
December 14, 2006: flash flood 2 miles from the centre of Mercer Island — 1 killed, $750,000 damage.
January 6, 2022: heavy rain event 10 miles from the centre of Mercer Island — 1 killed.
January 7, 2022: heavy rain event 10 miles from the centre of Mercer Island — 1 injured, $1.5 million damage.
Source: NOAA NCEI Storm Events Database, events whose starting point is on record, 1996 to June 30, 2026. Damage is the NWS estimate in the dollars of the year, not insured losses, and NWS notes that some reports are unverified.
Flood insurance claims, disaster declarations and FEMA risk ratings
Flood insurance policyholders in Mercer Island's ZIP code 98040 have filed 13 claims with the National Flood Insurance Program since 1980, and were paid $136,000 for buildings and contents, in the dollars of each year. 31% of the claims carry the name of a storm or flood event; the rest have no event name. Of the 128 Washington cities on this site with 10 or more claims, 10 have fewer than Mercer Island.
King County, which includes Mercer Island, has been named in 35 federal disaster or emergency declarations since 1964, 31 of them major disasters (by incident: 17 floods, 11 severe storms, 2 biological emergencies, 2 earthquakes). The latest major disaster declaration was Severe Storms, Straight-Line Winds, Flooding, Landslides, and Mudslides, on April 7, 2026. FEMA's National Risk Index gives King County a Very High rating for natural hazard risk overall; by hazard: Very High for inland flooding; Relatively High for heat waves; Relatively Moderate for tornadoes, coastal flooding and lightning; Very Low for hail and strong wind. It models the county's expected loss from all 18 hazards it covers at $1.68 billion a year, the highest of 39 Washington counties; of the hazards above, the largest share, $416.9 million (25%), is from inland flooding.
Claims: FEMA, OpenFEMA Dataset FIMA NFIP Redacted Claims – v3, summed over ZIP codes; payments in the dollars of each year, not adjusted for inflation. Declarations: Disaster Declarations Summaries – v2, by county. Retrieved October 25, 2026. This product uses the Federal Emergency Management Agency's OpenFEMA API, but is not endorsed by FEMA. The Federal Government or FEMA cannot vouch for the data or analyses derived from these data after the data have been retrieved from the Agency's website(s).
Risk ratings: FEMA, National Risk Index county table, December 2025 (v1.20), retrieved October 26, 2026; ratings compare counties nationwide, are meant for planning and are no substitute for a local risk assessment. This product uses the Federal Emergency Management Agency's National Risk Index dataset API or downloadable datasets but is not endorsed by FEMA. The Federal Government or FEMA cannot vouch for the data or analyses derived from these data after the data have been retrieved from the Agency's website(s).
What counts as a pass, the distances and the sources: how this storm history is built.