Canadian wildfire smoke to be a periodic problem into August across Midwest, Northeast
Prevailing winds will direct more wildfire smoke from western Ontario into the Midwest and Northeast often well into August. Needed rain to put out the fires may be scarce.
The sky continues to be blanketed under hazy and suffocating wildfire smoke from Canada across the Midwest and Northeast regions of the U.S. on July 16.
More episodes of wildfire smoke are in the offing for parts of Canada and the midwestern and northeastern United States as the weather pattern in the coming weeks does little to extinguish the ongoing flames.
"Some sporadic rain is in the forecast for western Ontario, which is the prime source of wildfire smoke entering the U.S. in recent weeks," AccuWeather Senior Meteorologist Reneé Duff said. "There will be a couple chances of meaningful rain Friday night through the weekend." The rain this weekend could be produced mostly by thunderstorms.
Drought and lightning are the main natural causes of wildfires.
Hundreds of large wildfires are burning across Canada and the U.S.
There are nearly 900 active wildfires in Canada, according to the Canadian Wildland Fire Information System. To date this year, there have been nearly 4,000 fires that have burned over 3 million hectares.
Even more fires have burned across the U.S. "So far this year, 41,236 fires have burned nearly 3.9 million acres across the United States," according to the (U.S.) National Interagency Fire Center newsroom. The Northwest continues to be the busiest region in the nation.
This map depicts large, active fires as flame symbols as of July 23, 2026. Smaller or recent prior fires appear as red dots. (Fire Information System for Resource Management System U.S./Canada)
Many of the fires are burning in remote, hard-to-combat, unreachable areas, which then rely on wet weather to extinguish them. Where feasible, aircraft and ground crews work feverishly to safeguard communities from the flames.
Sometimes containment efforts work, but most attempts only slow the progress of the fires enough to allow people in the path to evacuate. In backwoods areas, where there are no roads or the distance is too far to fly in tanker aircraft with visual ground support, the fires are left to burn and let nature take its course.
In this July 31, 2003, file photo showing a Canadair CL-215 scooper aircraft retrieving water from Lake MacDonald to fight a fire in Glacier National Park, Montana. (AP Photo/Douglas C. Pizac, File)
Insect infestations (Spruce Budworm, Emerald Ash Borer and Mountain Pine Beetle) and drought have damaged or killed scores of trees, which then become potential fuel during droughts, lightning activity and when humans create ignition sources. Resins from certain trees and brush can accelerate fire ignition and spread.
Smoke is a product of fires, and its density depends on available fuels. Certain types of evergreen and deciduous foliage can emit much more smoke than simple grassland fires.
Winds fan the flames and carry smoke for hundreds and thousands of miles. How high or low the smoke is relative to the ground depends on atmospheric conditions, such as turbulence, humidity and precipitation. High-flying smoke may only cause the sky to appear hazy. Low-lying smoke can pose serious health risks and create dangerously low visibility.
The main driver of smoke from their origin points in western Ontario to the Midwest and Northeast is the prevailing jet stream dip over the eastern part of North America. Steering winds from the northwest will scoop up the smoke and whisk it southeastward.
The amount of smoke will depend on whether swirls of clean air mix in from the southwest or from the north and northeast. While conditions will vary widely from location to location, day to day and hour to hour, the overall prevailing northwest to southeast propagation of the smoke is likely to continue into August or until enough rain falls on the fires to put them out.
The CSL Welland bulk carrier passes Windsor, Ontario, on the Detroit River amid poor air quality from smoke from Canadian wildfires on Thursday, July 16, 2026, in Detroit. (AP Photo/Paul Sancya)
Some of the smoke from fires in the western U.S. is also being carried northward into western and central Canada.
"It is possible that lasting relief from the Canada fire conditions may not happen until the colder weather season, when larger storms bringing rain and snow typically arrive from later in August to the autumn," AccuWeather Senior Meteorologist Matt Benz said.
As August progresses, the jet stream may retreat from its southward dip into the Northeastern states and take on a more west-to-east configuration. That setup could more often direct most of the smoke across less-populated areas of Canada.
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