But the hot weather did not relent east of the Cascade Range in Oregon and Washington, where excessive heat warnings remained in place. The National Weather Service forecast more heat in Idaho and Montana for the rest of the week.
A farm laborer died over the weekend in St. Paul, Oregon, according to the state's Occupational Health and Safety division. Officials there did not release any further details of that casualty and did not publicly identify the person.
For residents of Seattle and Portland, however, the more moderate weather meant a return to normal after several days of hunkering down in air conditioned homes or makeshift cooling centers.
"I feel like it was a snow day, but it's just hot. Nobody wanted to be outside for than 5 minutes. I felt a little lethargic and tired," said Ariel Black, a 29-year-old musician with the Portland-based wedding band Dancehall Days.
"We have a couple gigs this week I'm looking forward to because its gonna be nice out. I'll be out and about, I'll have a date night and sit outside," Black said.
The major Pacific Northwest cities of Portland and Salem in Oregon, and Seattle in Washington, trapped under a high-pressure dome, shattered temperature records again on Monday.
In Salem, Oregon's state capitol, temperatures reached 117 degrees Fahrenheit (47.2 degrees Celsius), the hottest since record-keeping began in the 1890s.
Seattle-Tacoma International Airport set an all-time high temperature of 106 Fahrenheit, breaking the record set one day earlier.
Portland's airport temperature reached 115 on Monday, breaking the all-time high for the third day in a row.
The brutal heat hit especially hard in Portland, where the typically cool city's infrastructure struggled to compensate.
Rail lines suspended service due to overheated electrical lines and bars and restaurants were forced to close after conditions became dangerous for cooks.
Even public swimming pools were shut down in the city on Monday after several lifeguards experienced heat-related illnesses.
Multnomah County, which encompasses Portland, said it would keep three of the cooling centers open until Wednesday morning, including one at the Oregon Convention Center.
On Tuesday, the cities of Portland and Bend, Oregon, banned all fireworks for the July 4 holiday, citing fire danger following the hot, dry weather.
Experts say the heatwaves that have descended on parts of the United States this year cannot be linked directly to climate change. But unusual weather patterns could become more common amid rising global temperatures, National Weather Service meteorologist Eric Schoening told Reuters this month. Reporting by Sergio Olmos in Portland Writing and additional reporting by Dan Whitcomb in Los Angeles; Editing by Aurora Ellis and Himani Sarkar