English: An unusually intense start to Canada’s wildfire season filled skies with smoke from large fires burning in Western Canada in May 2023. Then, at the beginning of June, scores of new fires raged in the Central Canadian province of Quebec, some of which were ignited by lightning.

The Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Terra satellite a true-color image of billowing from widespread fires in Quebec province on June 4. Shortly after the fires started, about 5,000 residents were ordered to evacuate near the city of Sept-Îles in the province’s east. As the fires grew, evacuations were extended to an additional 9,000 people in surrounding communities and in western Quebec’s Val-d’Or and Normétal municipalities. As of the evening of June 5, more than 160 wildfires were active in Quebec, most of them out of control according to CBC-Radio Canada.

Smoke from the blazes prompted air quality warnings across Quebec and Ontario. By June 5, Environment Canada had issued a severe special air quality statement for most of Quebec, including Sept-Îles, urging residents to wear respirators if they had to venture outside and to use air filters to recirculate and clean indoor air. On June 4, the air quality index for fine particulate matter (PM 2.5) was classified as unhealthy in southern Quebec and eastern Ontario, according to NOAA’s Aerosol Watch. Fine particulate matter from the smoke blew down to the U.S. Midwest, where it made the air quality unhealthy for sensitive groups in parts of Minnesota, Wisconsin, Illinois, and Michigan.

Fire season in Quebec usually starts in late May. In an average year, only 247 hectares (a square mile) of area would be burned by June 5, according to Quebec’s fire prevention agency (SOPFEU). But so far this year, 160,000 hectares (600 square miles) have burned. The fire prevention agency said the fierce start to the season has in part been due to high temperatures and dry conditions in the province.