An unusually intense start to Canada’s wildfire season filled skies with smoke in May 2023. Then, at the beginning of June, scores of new fires raged in the eastern Canadian province of Quebec, some of which were ignited by lightning.
Smoke from the blazes prompted air quality warnings across Quebec and Ontario. 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.