Much of the US Pacific north-west remained under an extreme heatwave as the weekend came to a close, with the National Weather Service calling temperatures intense, prolonged, record-breaking, unprecedented, abnormal and dangerous. Daytime temperatures were in the triple digits Fahrenheit, breaking records in places where many do not have air conditioning. Sunday’s forecasted temperature in Portland, Oregon, 112F or 44C, was set to break the all-time temperature record of 108F (42C) – a mark set a day earlier. The forecast called for another 112F/44C day on Monday. The temperature was expected to rise to a record 104F (40C) at the Seattle-Tacoma International Airport on Sunday and to reach 111F (43.9C) on Monday. King county closed several Covid-19 testing sites because of the heat. Seattle opened additional public library branches on Sunday and will again Monday to provide additional cooling centers, the Seattle Times reported. Seattle’s light rail trains may have to operate at reduced speeds because of excessive heat on the tracks, causing delays that could continue into the work week, Sound Transit said. The heat also moved into Idaho, where temperatures above 100F (38C) were forecast in Boise for at least seven days starting on Monday. Ontario, Oregon – a city near the Idaho border – could see at least a week of triple-digit temperatures, including a high of 109F (42.8C) on Wednesday, forecasters said. The high temperatures were also forecast to move into western Montana, beginning on Monday. Cities were reminding residents pools, splash pads and cooling centers were available and urging people to stay hydrated, check on neighbors and avoid strenuous activity. Still, about 3,000 athletes were scheduled to participate in an Ironman Triathlon in Coeur d’Alene, Idaho on Sunday. The race start was moved up to 5am. The event included a 2.4-mile swim, a 112-mile bike ride and a 26.2-mile marathon run. Organizers said they had 62,000lb of ice at hydration stations, misting stations and chilled towels to hand out to athletes, KHQ-TV reported. The Coeur d’Alene fire department brought in extra firefighters and paramedics. Sam Long of Boulder, Colorado won the race in eight hours, seven minutes and 42 seconds. The NWS in Coeur d’Alene said this week’s weather “will likely be one of the most extreme and prolonged heatwaves in the recorded history of the inland north-west. “Unprecedented heat will not only threaten the health of residents but will make our region increasingly vulnerable to wildfires and intensify the impacts of our ongoing drought.”