Wildland fire activity in Canada ramped up in July 2026, a time of year when lightning ignitions typically increase, according to aseasonal outlookpublished by several North American fire agencies.
The blazes sent smoke plumes pouring across the U.S. and Canada, affecting air quality in both countries.
This animation tracks brown carbon, the organic aerosols emitted by fires that give smoke plumes their characteristic yellow, orange, and brown tint.
Brown carbon is a major component of a fire’sPM2.5emissions, a type of air pollution that can aggravate cardiovascular and respiratory conditions.
Here, the plume drifts across North American skies from July 14 through July 20, 2026.
Data for the animation come from a version of theGEOS model, which assimilates data from satellites, aircraft, and ground-based observing systems.
In addition to satellite observations of aerosols and fires, the model also incorporates meteorological data such as air temperature, moisture, and winds to project the plume’s behavior.
On July 14, at the start of the animation, numerous fires had already cropped up, including more than180 in Ontarioand several in northern Minnesota.
Winds carried the smoke southeast, and by July 15, skies turned hazy andair quality declinedfrom southern Ontario in Canada to the Upper Midwest and Northeast in the U.S. July 16 and 17 saw air quality in many areas continue to plummet, including in Detroit, where it stayed in the hazardous range for severalconsecutive days.
Toronto, Chicago, New York City, and Washington, D.C., saw air quality ranging fromunhealthy to hazardous.
On July 19 and 20, smoke continued to affect air quality downwind, including in the Great Lakes region, according to the National Weather Service.
Storms began clearing it away in parts of the East, where air quality improved to good or moderate.
Meanwhile, firesin the Pacific Northwest began degrading air quality there.
The brown carbon shown in this animation represents organic carbon that comes specifically from wildfire smoke.
Wildfires also emit black carbon, or soot, which contributes to their PM2.5output.
Black carbon has long served as atracer for smoke plumes, but human sources—such as vehicle exhaust and industrial combustion—produce it too, blending in with the black carbon from fires.
The GEOS model has been able to make that distinction for brown carbon since February 2026, whenan updateenabled it to split organic carbon into its anthropogenic and biomass-burning components.
NASA Earth Observatory animation by Lauren Dauphin, usingGEOS-FPdata from the Global Modeling and Assimilation Officeat NASA GSFC. Story by Kathryn Hansen.
The ConversationYes, breathing wildfire smoke can harm your health – here’s what you can do to protect yourself. Accessed July 21, 2026.
NASA’s Global Modeling and Assimilation OfficeSplitting Anthropogenic and Biomass Burning Sources of Organic Carbon in GOCART-2G. Accessed July 21, 2026.
NASA’s Scientific Visualization StudioLong-range Transport of 2026 Canadian Wildfire Smoke into the United States. Accessed July 21, 2026.
National Interagency Fire Center, Natural Resources Canada, and Servicio Meteorológico NacionalNorth American Seasonal Fire Assessment and Outlook. Accessed July 21, 2026.
The New York TimesWhen Will the Wildfire Smoke Clear?Accessed July 21, 2026.
U.S. Environmental Protection AgencyAirNow: Interactive Map of Air Quality. Accessed July 21, 2026.
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