A heat dome has enveloped the Pacific Northwest, driving temperatures to extreme levels — 110 degrees in some spots — and creating dangerous conditions in a part of the country unaccustomed to oppressive summer weather or air-conditioning.
Temperatures reached 102 degrees on Saturday at Seattle-Tacoma International Airport, the second-hottest day ever recorded at the airport since 1945 and only the third time that the high there reached triple digits, according to official records.
At Portland International Airport in Oregon, a high temperature of 108 degrees was recorded on Saturday, surpassing the previous record of 107 degrees.
The average high temperature for this time of year at the airport is about 73 degrees, said forecasters, who predicted that it would be even more stifling on Sunday and Monday.
“Goodnight cruel sauna — I mean, Seattle,” Maddie Kristell, a meteorologist for the National Weather Service in Seattle, posted on Twitter on Saturday night, along with a photo of two air-conditioning units that she had running.
The National Weather Service issued an excessive heat warning for virtually all of Washington and Oregon, as well as sections of California, Idaho, Montana and Nevada.
The warning will remain in effect until Monday night for much of Oregon and Washington, where state and local entities opened cooling centers for residents.
The meteorological anomaly, which forecasters attributed to an upper-level ridge of high pressure stalled over British Columbia, even led the National Park Service to warn hikers about how snow and ice are melting faster on Mount Rainier in Washington.
“Even higher elevations such as Paradise won’t escape the extreme heat hitting the PNW,” the national park said on Twitter.
The heat is expected to linger in areas farther east until at least the middle of the week, according to the National Weather Service. Its forecast office in Spokane, Wash., predicted high temperatures of at least 112 degrees from Sunday through Wednesday.
In preparation for the heat wave, Gov. Jay Inslee of Washington suspended limits on the number of people who could be accommodated at cooling centers run by the government and by nonprofit groups in the state.
The limits had been put in place as part of public health emergency orders during the coronavirus pandemic.
The Seattle Library said on Sunday morning that it was opening additional air-conditioned branches on Sunday and Monday to provide people refuge from the heat.
The Oregon Health Authority announced on Friday that it had also lifted limits on the number of people who could gather at swimming pools, movie theaters and shopping malls.
At the Holiday Inn Express & Suites in North Seattle, the television station KING 5 reported that the hotel’s air-conditioned rooms were fully booked this weekend, the first time since the pandemic began.
“It’s been a blessing,” Ron Oh, the hotel’s general manager, told the station.
Mr. Oh, who is also the board chairman of the Washington Hospitality Association, said the phone was ringing constantly with questions about room availability.
“It generally comes down to, ‘Oh, my God, it’s so hot, I need a place with air-conditioning,’” he said.