Mercer Island, WA Tornado History — 10 Tornadoes Since 1950
How many tornadoes has Mercer Island, WA had?
Mercer Island has had 10 tornadoes on record within 25 miles since 1950, including 1 violent (EF3+) tornado.
When was the most recent tornado near Mercer Island?
The most recent tornado within 25 miles of Mercer Island was an EF2 on December 18, 2018.
When is tornado season in Mercer Island?
December is historically the peak month for tornadoes near Mercer Island, with 3 on record. Spring through early summer (April–June) generally sees the highest activity across most of the central and southern United States.
At a Glance
Recent Tornado Activity Near Mercer Island
The last 20 years of confirmed tornadoes within 25 miles — 2 total, averaging 0.1 per year over this window.
Tornadoes by Decade
Tornadoes by Enhanced Fujita Rating
F0–F5 ratings (pre-2007) are grouped with their EF equivalents. The Enhanced Fujita scale replaced the original Fujita scale in February 2007.
Tornadoes by Month
Have any tornadoes near Mercer Island been fatal?
No fatalities are on record within 25 miles of Mercer Island from any of the 10 tornadoes since 1950, though 1 injuries have been reported. NOAA Storm Prediction Center records.
Notable Tornadoes Near Mercer Island
About Tornadoes in Mercer Island
This overview was written April 23, 2026. The tornado counts and notable-event figures elsewhere on this page reflect the latest data and may differ from this summary.
Mercer Island, Washington and the surrounding 25-mile radius have experienced 10 documented tornadoes since 1950, according to the NOAA Storm Prediction Center. This relatively modest total reflects the Pacific Northwest's generally lower tornado frequency compared to regions farther east, though the area is not immune to these events. Notably, none of the recorded tornadoes within this radius have resulted in fatalities.
The temporal distribution shows clustering in certain decades, with three tornadoes occurring in both the 1960s and 1990s, and two in the 2010s. Single events were recorded in the 1970s and 2000s. December stands out as the peak month with three tornadoes on record, an unusual pattern that diverges from the spring and early summer peak typical of most U.S. regions. This winter concentration likely reflects the area's susceptibility to tornadoes associated with strong Pacific storm systems rather than the classic supercell thunderstorms more common in other parts of the country.
In terms of intensity, the majority of tornadoes have been weak, with five rated EF0 and three rated EF1 on the Enhanced Fujita scale, which measures tornado strength based on damage. However, the area has also seen one EF2 and one EF3 tornado, demonstrating that stronger events, while rare, can occur. The most significant recent tornado was an EF2 that struck on December 18, 2018, causing $1,180,000 in property damage along a 1.4-mile path with a maximum width of 285 yards. This event was simultaneously the costliest, widest, and most recent tornado on record for the area.
The longest-tracked tornado occurred much earlier, on August 18, 1964, when an F0 tornado traveled 5.2 miles with a maximum width of only 30 yards, causing no reported damage. While tornado activity near Mercer Island remains infrequent compared to many other U.S. locations, the historical record demonstrates that residents should maintain awareness of severe weather potential, particularly during the winter months when Pacific storms are most active.