More than 10,700 flights in the United States were delayed on July 17, 2026, due to heavy smoke from over 900 active wildfires burning across Canada, according to Travelers Today. The smoke caused hazardous air quality across the U.S. Midwest, Great Lakes, and East Coast, impacting airspace visibility and airport operations.
Airlines Issue Waivers Amid Flight Delays
United Airlines issued a travel advisory on July 17 for 17 airports affected by smoke in the U.S. and Canada, including Detroit Metropolitan Airport, Toronto Pearson International Airport, Buffalo, Syracuse, Rochester, Duluth, and several airports in Michigan, Wisconsin, and New York. United allowed passengers with tickets purchased by July
16 to rebook flights from July 16 to July 20 without change fees or fare differences within the same cabin and route, with the rebooking window closing July 20.
Delta Air Lines implemented a Midwest Air Quality Advisory covering flights from July 16 through July 18. This included airports in Detroit, Minneapolis-St. Paul, Milwaukee, Green Bay, Grand Rapids, Madison, and other cities in Michigan and Wisconsin. Delta’s rebooking waiver extended through July 21.
American Airlines reported that 42 percent of its flights were delayed on July 17, more than double its 2026 average delay rate. American’s waiver deadline for no-cost
rebooking was July 18, but passengers can still apply unused ticket value to future travel within one year of ticket issuance.
Airport Delays and Airspace Restrictions
Philadelphia International Airport experienced 365 flight delays and 12 cancellations on July 16, with over 200 delays reported on July 17 amid a Federal Aviation Administration (FAA) ground delay program. Smoke-related visibility issues affected air traffic control capacity, particularly at major hubs including Philadelphia, Chicago O’Hare, Detroit, and airports throughout the Great Lakes region.
Chicago’s Air Quality Index (AQI) reached approximately 153 on July 19 at 6 a.m., labeled as unhealthy air quality. Detroit recorded an AQI of roughly
600 on July 16, surpassing its previous historical maximum. Northern Minnesota measured PM2.5 levels exceeding 600 micrograms per cubic meter on July 16 and 17, far above the Environmental Protection Agency’s hazardous threshold of 500 AQI.
Smoke Air Quality Warnings Continue
The National Weather Service forecasted a third wave of smoke moving back into the Great Lakes region by July 19, with unhealthy air persisting in Chicago, Detroit, and parts of the Northeast. Cities such as Chicago, Milwaukee, Pittsburgh, and Washington ranked among the world’s worst polluted on July 17. The Environmental Protection Agency advised limiting outdoor exertion at AQI above 150 and avoiding outdoor
activity entirely at AQI above 200. N95 or KN95 masks were recommended for filtering particulate matter; standard cloth masks offered insufficient protection.
FIFA confirmed smoke conditions at MetLife Stadium in East Rutherford, New Jersey, did not threaten the World Cup Final on July 17, despite residents being warned to heed air quality precautions.
Political and Environmental Context
On July 17, President Donald Trump threatened to increase tariffs on Canadian goods to cover what he termed the “incalculable” costs of the wildfire smoke, calling Canadian fire management “Willful Negligence.” He stated these costs “must of necessity be added to the TARIFFS Canada is currently paying.”
However, legal analysts and court rulings indicate the U.S. administration lacks clear authority to impose such tariffs in response to wildfire smoke, as wildfires are not trade practices covered under existing trade laws.
Canadian Prime Minister Mark Carney countered that responding to climate change is “the responsibility of all countries, including the United States,” noting the U.S. withdrawal from international climate initiatives. Emergency Management Minister Eleanor Olszewski reported Canada has invested $12 billion in forest sustainability and fire prevention since 2020, operating under bilateral wildfire cooperation agreements with the U.S. originally signed in 1982 and reaffirmed in 2025.
Ontario Premier
Doug Ford criticized U.S. officials blaming Canada for the fires, highlighting Canadian firefighting aid to California last year and challenging the U.S. to remove softwood lumber tariffs exceeding 45 percent, including a 10 percent duty imposed in October 2025.
Climate experts attribute the wildfires to extreme heat waves, not forestry management failures. On July 13, temperatures in Ontario were 25.2 degrees Fahrenheit above average, a level “virtually impossible” without climate change, said Shel Winkley, Chief Meteorologist at Climate Central. The 2026 Canadian wildfire season was tracking at 134 percent of its 10-year average through mid-July, while U.S. wildfires burned over
5,740 square miles, 31 percent above the 10-year average.
