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Hot weather records: The history of Seattle's heat waves

Here’s a look back at some of Seattle’s most sweltering moments.

Record-breaking heat is in the forecast for Seattle and the Puget Sound region this weekend and into early next week. Temperatures are expected to climb into the 90s by Saturday, and possibly reach triple digits.

Forecast lows for the weekend around Seattle are expected to remain near 70 degrees, providing less relief from the heat at night.

The hottest Seattle’s ever gotten was 103 degrees on July 29, 2009. Seattle also hit 100 degrees on July 20, 1994, and had reached 99 degrees three times in 1991, 1981, and 1960.

Since record-keeping began, Seattle has only seen one 100-degree day in June; that was June 9, 1955, at the old Federal Building in downtown Seattle where records were kept from 1894-1971.

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It isn’t a coincidence that two of Seattle’s hottest days were in July – that’s statistically the hottest month of the year, reaching a daily high of 75.6 degrees on average. August is typically just a hair cooler; highs typically get to 75.3 degrees.

As for heat waves, Seattle has experienced two where high temperatures stayed in the 90’s for five straight days: July 2015 and August 1981. There have also been eight times where temperatures were similarly sweltering for four consecutive days, half of which were in the last 15 years.

Unsurprisingly, in 2015, Seattle also saw the most days above 90 degrees, recording 12. We came close in 2018 with 11 days above 90 degrees.

Most of the heat comes in summer, but it has gotten pretty unseasonably toasty before. The earliest in the year that Seattle broke 80 degrees was April 1, 1987, when temps soared to 82 degrees. The latest in the year Seattle hit 80 degrees was October 1, 1987.