More than 800 wildfires are burning across Canada, sending thick plumes of smoke south into the United States and triggering air quality alerts across more than 20 states from Minnesota to New York.
The smoke has degraded air quality for millions of Americans. Detroit currently has the worst air quality in the world, according to Swiss air quality tracker IQAir, followed by Toronto, then Minneapolis and Chicago.
The Canadian Interagency Forest Fire Centre reported 857 fires actively burning, including 23 new fires that started on Thursday. The vast majority are burning out of control, according to the Canadian Wildland Fire Information System. A large cluster in northwestern Ontario is responsible for sending thick smoke across Thunder Bay and Toronto, with lower concentrations drifting over the Great Lakes and above New York.
Air quality degrades across the Upper Midwest and Northeast
The US Air Quality Index program deems air quality in large parts of Michigan and Minnesota “hazardous,” the most severe ranking. Officials urge residents there to stay indoors. Parts of Illinois, Wisconsin, Michigan, and Ohio are rated “very unhealthy,” the second-highest tier. In western New York state, air quality on Thursday is considered “very unhealthy,” while the New York City metro area registers as “unhealthy.” Air quality alerts span the Upper Midwest, the Great Lakes region, and into the Northeast, the National Weather Service said in an update on Thursday.
The National Aeronautics and Space Administration said winds carried smoke from the Ontario fires across southern Ontario, Quebec, and the US Midwest and Northeast. Skies turned shades of gray and yellow across many areas, and the sun glowed orange through the haze. The National Weather Service in Detroit warned that smoke is expected to be most dense on Thursday afternoon and night with reduced visibilities.
New York officials extended the city’s heat emergency plan and activated air quality emergency protocols on Wednesday. Hundreds of cooling centers opened citywide. Governor Kathy Hochul announced that more than 100,000 N95-style masks were being made available to counties in need, with additional masks for commuters at Penn Station and Grand Central. “It’s dangerously hot and smoke from Canadian wildfires has worsened our air quality, which means New Yorkers need to be extra vigilant to stay safe,” Mayor Zohran Mamdani said. He urged residents to stay in air-conditioned spaces, limit outdoor activity, and stay hydrated. Officials warned that this could become the city’s “most significant smoke event” since 2023, when Canadian wildfires pushed air quality to hazardous levels and blanketed the city in an orange haze.
Frustration and cooperation at the border
Republican lawmakers in Michigan penned an open letter to Canadian Prime Minister Mark Carney asking for better management of the country’s wildfires, expressing frustration for the third year in a row. “A year has passed, the season has come around again, and nothing has changed except that our patience has run out,” the letter, signed by four House representatives, said. US Ambassador to Canada Pete Hoekstra struck a more diplomatic tone. “This challenge knows no borders,” he said in a statement on Wednesday. “The United States will continue to coordinate closely with Canada, just as we have for more than four decades of shared wildfire emergencies,” he added.
In northern Ontario, the wildfires have forced hundreds from local First Nations communities to evacuate, with videos showing some fleeing by boat. Homes and buildings have been damaged extensively by the flames, said Anishinabek Nation Grand Council Chief Linda Debassige. A freight train in Ontario was surrounded by wildfire flames on Wednesday, as workers requested an emergency rescue. Canadian National Rail said all workers trapped outside Armstrong were safely rescued. Operations have been temporarily suspended in the region.
Massachusetts Senator Ed Markey said the smoke is “darkening skies and getting in our lungs across the state.” “The climate crisis is here and it does not stop at our borders,” he added.
Northwesterly winds will continue to push smoke into northern US states through the weekend. There are concerns that smoke will drift into New Jersey. Sunday’s World Cup final is scheduled there. A change in wind direction by Monday is expected to steer smoke across Quebec, bringing an improvement in air quality further south in the US.