Western North American extreme heat virtually impossible without human-caused climate change
During the last days of June 2021, Pacific northwest areas of the U.S. and Canada experienced temperatures never previously observed, with records broken in many places by several degrees Celsius. Multiple cities in the U.S. states of Oregon and Washington and the western provinces of Canada recorded temperatures far above 40ºC (104 ºF), including setting a new all-time Canadian temperature record of 49.6ºC in the village of Lytton. Shortly after setting the record, Lytton was largely destroyed in a wildfire [ 1 , 2 ]. The exceptionally high temperatures led to spikes in sudden deaths, and sharp increases in hospital visits for heat-related illnesses and emergency calls [ 3 , 4 , 5 ]. Heatwaves are one of the deadliest natural hazards and this heatwave affected a population unaccustomed and unprepared for such extreme temperatures, for instance with most homes lacking air-conditioning [ 6 ]. Currently ava