Washington and Oregon endured scorching temperatures, and a sense of deja vu hung in the air as the region baked in the second intense heatwave of the summer.
Temperatures were expected to soar to triple digits again on Friday in Portland and Seattle. Forecasters said hot weather and wildfire smoke would pose a problem through the weekend.
Temperatures in Portland reached 103F (39C) by late afternoon on Thursday – 20 degrees above average – and Seattle reached highs in the 90s. In Bellingham, Washington, the high hit 100F for the first time on record.
Although the temperatures were not due to be as severe as during the heatwave in late June, when some areas exceeded 115F (46C), several cities declared excessive heat warnings.
Much of the north-west was under such a warning through Saturday. The National Weather Service said heat advisories and warnings were also in effect from the midwest to the north-east and mid-Atlantic through at least Friday.
In Beaverton, Oregon, where temperatures could reach 102F again on Friday, the community center was offering overnight air-conditioned shelter for those in need.
Portland’s 102F on Thursday was hotter than temperatures recorded in Phoenix, where the high in the desert city was a below-normal 100F. Portland typically sees temperatures in the 80s during August.
Volunteers scrambled to hand out water, portable fans, popsicles and information about cooling shelters to homeless people living in isolated encampments on the outskirts of the city.
Oregon fire officials are braced for high temperatures and lightning raising the wildfire risk over the weekend.
“We do have a large amount of fire across all of our lands. The next 72 hours will be critical,” Oregon’s fire marshal, Mariana Ruiz-Temple, told reporters.
The huge Bootleg fire in southern Oregon has been almost entirely contained, with officials making efforts to keep it that way, amid more than a dozen wildfires alight in the state, many started by lightning strikes.
The Oregon department of forestry’s chief of fire protection, Doug Grafe, said that crews had “lots of confidence we’re going to hold that [Bootleg] fire where it is now”.
Oregon’s governor, Kate Brown, and the Portland mayor, Ted Wheeler, had declared a state of emergency earlier in the week due to the extreme heat.
Brown said: “Please treat these hot temperatures seriously. Heat-related illnesses are preventable. Please learn the symptoms. If you don’t have air conditioning in your home, make a plan right now to find a cool location you can access.”
Seattle’s mayor, Jenny Durkan, tweeted on Thursday: “Dangerously high temperatures ahead for Seattle.” She included a map of cooling center locations, a list of drinking fountains and advice for staying cool.
Seattle officials said they would be monitoring key infrastructure such as power systems, water systems, roadways and bridges, and would be coordinating outreach teams who can help some of the most vulnerable people deal with the high temperatures.
Officials in Washington and Oregon urged residents to stay hydrated, check on family and neighbors and make use of the dozens of cooling centers at libraries, community centers and other spaces throughout the region. In Portland, the local transit system was offering free rides to cooling centers during the heatwave.
A recording sent to Portland residents warned: “Heat can kill. Make a plan to stay cool.”
The heatwave comes mere weeks after record-high temperatures resulted in hundreds of deaths across the US Pacific north-west and western Canada. In Oregon, 96 people were killed in the June heatwave, including a farm worker.
Meteorologists reported that the extreme temperatures came from two pressure systems, while a study from World Weather Attribution determined that the heatwave would have been “virtually impossible without human-caused climate change”.
Officials attributed this week’s heatwave to a high-pressure system or heat dome over the north-east Pacific Ocean. It is expected to move to the east at the end of the weekend.
Larry O’Neill, Oregon’s state climatologist, previously told the Guardian: “These sorts of heatwaves are being made worse and more impactful because of climate change.”
