Summer 2021 was the hottest in 126 years of records in the United States, according to the NOAA. The average temperature for all of the Lower 48 from June through August was 2.6 degrees above average. (Adobe Stock)
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Aug 18, 2025
By Isobel Charle
A new report synthesizing more than 70 studies on the Northwest’s historic 2021 heat wave found similar extreme heat events are likely to happen more often.
That summer, the hottest temperature ever recorded in Washington, 120 degrees, was reached in Hanford.
Karin Bumbaco, deputy climatologist for the State of Washington, and co-author of the report, said research found by 2050, the Northwest will have between a 10% and 33% chance of a similar heat event happening any given summer.
“That’s quite an increase, especially if you look at that higher end, where one in three summers you could expect to have a heat wave of a similar magnitude to 2021,” Bumbaco pointed out.
The 2021 heat dome resulted in the deaths of about 500 people across the Northwest. That summer, 156 all-time daily maximum temperature records were tied or broken, including the warmest temperatures ever recorded in Washington, Oregon and Canada.
Bumbaco added, though the research varied widely, it found similar heat events are more likely to occur again in part because of climate change.
“By 2050, climate change increases the likelihood of a similar event to 2021 by an additional 6% to 175%,” Bumbaco explained.
After the heat wave, Bumbaco noted Oregon and Washington both implemented new rules to protect outdoor workers from heat, requiring employers to provide access to shade, cool drinking water, and additional rest breaks. She added standards are changing for indoor spaces as well.
“More and more people are getting air conditioning, new construction is having it because of recent heat events that we’ve had,” % observed. “It is something that will likely continue to change in the area.”
The report notes during a heat dome, high pressure in the atmosphere acts like a lid, trapping hot air underneath and preventing it from rising, causing more extreme temperatures.