Why It Matters
Smoke from more than 830 wildfires burning across Canada is spreading across the upper Midwest and Northeast, creating hazardous air quality conditions across multiple states while a simultaneous heat wave drives temperatures to dangerous levels. The combination poses health risks to vulnerable populations and could complicate outdoor activities across a vast swath of the country.
What Happened
Smoke from Canadian wildfires began blanketing the upper Midwest and Northeast on Wednesday, July 15, with visible haze descending on major population centers from the Great Lakes region through New England. An orange haze covered the New York City skyline as air quality deteriorated across the state, prompting health advisories across multiple regions.
The smoke originated from wildfires burning primarily in west-central Ontario and spread southward into the United States. By Wednesday evening, smoke was expected to stretch from Buffalo to Philadelphia, with heavy concentrations streaming through Green Bay, Milwaukee, Grand Rapids, Detroit, and Toronto. Conditions in parts of northern Wisconsin and Minnesota were described as extreme, with very heavy smoke visible over Duluth and Marquette by Wednesday morning.
New York City officials issued an Air Quality Health Advisory for the entire state on Thursday as concentrations reached unhealthy levels across the city, the Eastern Lake Ontario region, Central New York, and parts of Western New York. The city began distributing free masks to residents. Air quality alerts extended from Minnesota to New York City, covering entire states of Wisconsin and Michigan.
Poor air quality conditions were expected to persist through Thursday before weather patterns brought relief. Rain was forecast for Friday across the upper Midwest and Saturday for the Northeast, with conditions expected to improve as systems move through.
By the Numbers
830+ — wildfires burning across Canada
More than a dozen — wildfires in northern Minnesota alone
104 degrees — heat index in New York City on Wednesday
105 degrees — heat index in Washington D.C. on Wednesday
107 degrees — heat index in Philadelphia on Wednesday
High 90s to triple digits — expected temperatures across the Northeast and upper Midwest Wednesday and Thursday
Concurrent Heat Emergency
The smoke event coincided with a significant heat wave affecting the eastern United States. Minneapolis was under an extreme heat warning through Thursday with a heat index near 100 degrees, while major East Coast cities faced dangerous conditions. The heat index in New York City was expected to feel like 104 degrees, with Washington D.C. at 105 degrees and Philadelphia reaching 107 degrees. Wednesday was forecast to be the hottest day of the Northeast heat spell.
An extreme heat warning was also issued for the Los Angeles area Wednesday through Thursday night, with highs expected near 96 degrees across Los Angeles and Orange counties.
Zoom Out
Major smoke events from Canadian wildfires affecting U.S. air quality have become more frequent in recent years. In June 2023, smoke from Canadian wildfires similarly turned New York City skies orange, creating comparable air quality challenges across the Northeast. The pattern reflects broader shifts in wildfire activity and atmospheric conditions affecting both countries.
The current event demonstrates how transnational environmental challenges can rapidly affect population centers across international borders, with air quality impacts extending hundreds of miles from the fire sources. The combination of widespread wildfires and extreme heat creates compounding public health challenges requiring coordinated response across multiple jurisdictions.
What’s Next
Conditions are expected to improve Friday and Saturday as precipitation moves through affected regions. Air quality officials will continue monitoring readings throughout the week, and public health advisories will remain in effect until concentrations decline to acceptable levels. Residents in affected areas have been advised to limit outdoor activities, use air filtration masks, and monitor official air quality indices for their specific regions.