Updated at 6 p.m.
Record-high heat is forecast in the normally mild-weathered Pacific Northwest this weekend, raising concerns about wildfires and the health of people in a region where many people don't have air conditioning.
City officials in Seattle were opening libraries as cooling centers and crews were being sent to places in Oregon where the risk of wildfires was high.
The National Weather Service has issued an excessive heat watch and predicted “dangerously hot” conditions Friday through at least Tuesday. The heat wave will cover portions of Washington, Oregon and Idaho, with temperatures rising to 114 degrees Fahrenheit in places, the agency said.
“This will likely be an historic heat wave,” the agency said. “Chances are good that many long-standing records will be broken."
Among those might be the record-high temperature for Spokane of 108 degrees Fahrenheit, set in 1921 and 1968, the Weather Service said.
AccuWeather meteorologist Bernie Rayno warned that the heat wave is arriving in an area where many people do not have air conditioning. That's especially true west of the Cascade Range, where cities such as Seattle and Portland typically enjoy more moderate weather.
According to the U.S. Census Bureau’s American Housing Survey of 2015, only one-third of households in Seattle had air conditioning, as the average high temperature in June is 71 degrees. Nationally, 89% of households have air conditioning.
In Oregon, forecasters predicted record-setting weekend temperatures between 102 and 106 degrees — and possibly higher — in the Portland metropolitan area. The hottest temperature ever recorded in Portland was 107 degrees, in 1965 and 1981. Cooling centers will open in the Portland area on Friday.
The city of Seattle will open more than 30 cooling centers, spray parks and an emergency shelter to provide residents relief. Mayor Jenny Durkan says people can take steps to protect themselves during the heat wave.
"Stay where it’s cool. Do not overexert yourself. It’s a good time to stay inside," Durkan said Thursday. "If you don’t have air conditioning or if your home is hot, theaters, restaurants, museums, libraries, places that are air conditioned – malls – those are good places to go and spend time."
Seattle leaders also encouraged people to drink plenty of water, especially if you work outside.
Wading pools and spray parks will open beginning Saturday. Several neighborhood library branches, community centers and senior centers will be available as cooling centers throughout the city.
On Saturday morning, an emergency shelter will be open at Fisher Pavilion at Seattle Center to provide relief for people experiencing homelessness.
Information about Seattle cooling centers and other facilities can be found here.
In Pierce County, the Department of Emergency Management and other agencies will have cooling centers open through the beginning of next week. Pierce Transit is offering free transportation to those centers for people seeking relief from the heat.
Communities scrambled to initiate burn bans in the Portland area, and fire crews were pre-positioned in high-risk wildfire areas. The heat could exacerbate efforts to fight several fires already burning in central and southern parts of the state.
The Bonneville Power Administration, the federal agency responsible for electrical supply in the Northwest, did not expect the heat to produce rolling blackouts like those that have happened in other parts of the country during heat waves.
“We’re in pretty good shape,” said Doug Johnson, spokesman for the Portland-based agency.
He noted the Columbia Generating Station nuclear power plant is back on line after a spring refueling outage. There is also plenty of water behind hydroelectric dams, such as the giant Grand Coulee Dam, to turn electric turbines, the agency said. Hydropower is a major electricity source in the Northwest.
Meanwhile, the Red Cross warned of increased wildfire risks, because of high temperatures coupled with severe drought conditions.
“After back-to-back years of record-breaking wildfires, this year it’s more critical than ever to get ready now,” said Alex Dieffenbach, head of the Northwest Region of the Red Cross. "Wildfires are dangerous and can spread quickly, giving you only minutes to evacuate.”
The Red Cross suggested people create an evacuation plan, build an emergency kit with food and water and plan for dealing with their pets.
“Because of the pandemic, include a mask for everyone in your household,” the Red Cross said.
KNKX's Rebekah Way and Kate DeWeese contributed to this report.
Gillian Flaccus of The Associated Press contributed to this report from Portland.