More than 10,700 flights in U.S. airspace were delayed on July 20, 2026, as smoke from over 900 active Canadian wildfires reduced visibility and forced airspace closures across the Midwest, Great Lakes, and East Coast regions.
Airline Travel Advisories and Flight Disruptions
United Airlines issued an air quality travel advisory on July 17 covering 17 airports in the U.S. and Canada, including Detroit, Toronto Pearson, Buffalo, and Syracuse. United allowed passengers with tickets purchased on or before July 16 to rebook flights scheduled for July 17 or 18 to dates through July 20 without change fees in the same cabin.
Delta Air Lines issued a Midwest
Air Quality Advisory affecting airports such as Detroit, Minneapolis-St. Paul, Milwaukee, Green Bay, and Madison for flights between July 16 and 18. Delta permitted rebooking at no fare difference through July 21 within the same cabin class.
American Airlines reported that 42% of its flights on July 17 were delayed, more than double its 2026 average delay rate of roughly 20%. American’s no-cost change waiver expired July 18, though unused ticket values remain applicable toward future flights within one year.
Philadelphia International Airport implemented an FAA ground delay program on July 16, resulting in 365 delays and 12 cancellations. Other
major hubs affected by delays included Chicago O’Hare and Detroit.
Air Quality and Regional Impact
The National Weather Service forecasted a third wave of wildfire smoke to affect the Great Lakes region on July 19 and 20, impacting cities such as Chicago and Detroit. Chicago recorded an Air Quality Index (AQI) of approximately 153 at 6 a.m. on July 19, ranking it the second most polluted major city globally that morning.
Northern Minnesota and Detroit experienced hazardous AQI levels exceeding 600 during the week of July 13-17, which is well above the Environmental Protection Agency’s 500-point hazardous threshold. Cities including Milwaukee, Pittsburgh, and Washington, D.C.
also recorded severe air pollution levels.
The Environmental Protection Agency recommends limiting or avoiding outdoor physical activity at AQI levels above 150 and 200, respectively. For protection against fine particulate matter (PM2.5), N95 or KN95 masks are advised as standard cloth masks do not filter effectively.
Political and Regulatory Responses
On July 17, then-President Donald J. Trump posted on Truth Social that the costs of Canadian wildfire smoke “must of necessity be added to the TARIFFS Canada is currently paying.” The legal basis for this proposal is unclear following a Supreme Court ruling on February 20, 2026, which limited presidential tariff powers under the
International Emergency Economic Powers Act (IEEPA).
The 10% global tariff under Section 122 of the Trade Act is set to expire on July 24, and the use of Section 301 tariffs would require a finding of unjustifiable trade practices, which wildfires do not constitute. The U.S. Trade Representative declined to renew the Canada-United States-Mexico Agreement (CUSMA) as of July 1, 2026, adding uncertainty to future tariffs.
Canadian officials rejected the tariff threat. Prime Minister Mark Carney said addressing climate change is “the responsibility of all countries, including the United States,” noting the U.S. withdrawal from climate initiatives. Emergency Management Minister
Eleanor Olszewski reported Canada has invested $12 billion in forest sustainability and fire prevention since 2020.
Ontario Premier Doug Ford criticized the U.S. administration, highlighting Canada’s assistance with U.S. wildfires last year and calling for the removal of U.S. softwood lumber tariffs exceeding 45%, including an additional 10% duty imposed in October 2025.
Climate and Wildfire Trends
Climate scientists attribute this year’s Canadian wildfires to a record-breaking North American heat wave influenced by climate change. On July 13, 2026, temperatures in Ontario were 25.2°F above average, a phenomenon described by Climate Central meteorologist Shel Winkley as nearly impossible without climate change influence.
The National
Interagency Fire Center reported U.S. wildfires have burned over 5,740 square miles in 2026, 31% more than the 10-year average. The Canadian wildfire season is at 134% of its 10-year average through mid-July.
Meanwhile, the Trump administration plans to close several wildfire smoke research laboratories, including the Pacific Wildland Fire Sciences Lab, vital for smoke monitoring and forecasting.
