Portland, Oregon, and other parts of the Pacific Northwest broke all-time heat records on Saturday as residents of the typically mild region emptied stores of fans and portable air conditioners. Temperatures are forecast to rise even higher on Sunday and Monday. "If you're keeping a written list of the records that will fall," the National Weather Service in Seattle tweeted, "you might need a few pages by early next week." The NWS's Spokane office warned the "heat will be historic, dangerous, prolonged and unprecedented." 

In Portland, where temperatures hit 108 degrees Saturday, topping the previous record of 107, the city has opened up three cooling shelters. The Dalles, Oregon, hit 112 degrees on Saturday. The Northwest is sweltering under a "heat dome" — a tall mass of hot air that sits over a region, keeping clouds and normal weather patterns at bay — a byproduct of the changing climate, experts say. "We know from evidence around the world that climate change is increasing the frequency, intensity, and duration of heat waves," says Kristie Ebi, a professor at the University of Washington. "We're going to have to get used to this going forward."