By Ben Noll
Smoke from relentless wildfires in Canada was expanding across the Northeast early Monday after a weekend of smoke-filled air across the Midwest and Great Lakes. In the coming days, the smoke will spread across the Atlantic and toward Europe.
A high-pressure system will settle near the East Coast this week, which would normally bring generally clear and pleasant weather. However, because of the prevalence of wildfire smoke, that won’t be the case. The smoke will get trapped underneath the lid of high pressure, with weak winds unable to blow the smoke away for much of the week.
Air quality alerts are in effect for a dozen northern states as of early Monday, warning of code orange and code red air quality levels — which range from unhealthy for sensitive groups to unhealthy for all.
Detroit, Chicago and Canada’s Montreal and Toronto, were in the top 10 worst cities for air quality on the planet early Monday, according to IQAir.
Wildfire smoke will also blow thousands of miles across the Atlantic, reaching Ireland on Tuesday and Britain, Belgium, the Netherlands and Germany on Wednesday.
Meanwhile, in the West, elevated-to-critical fire conditions are forecast across several states starting on Monday, as smoke from several active fires — such as the Gifford Fire, which has prompted evacuations near San Luis Obispo, California — fuel hazy skies.
Places that can expect a smoky week
The smokiest regions of the country will be the Midwest, Great Lakes, Northeast and Southwest this week.
Eastern states
Significant amounts of near-ground wildfire smoke stretched from eastern Iowa to Maine as of early Monday — including in Chicago; Green Bay, Wisconsin; Detroit and Buffalo; as well as Toronto, Ottawa and Montreal.
This band of smoke will drift southward through the day, reaching Boston, New York and Philadelphia. Surface smoke concentrations are forecast to generally remain low in the Mid-Atlantic, including Baltimore and D.C., although there will probably be a noticeable haze from smoke aloft.
Smoke will spread more than 5,000 miles from Canada to the United States to Europe this week. (Ben Noll/Data source: Copernicus Atmosphere Monitoring Service)
Smoke is forecast to remain anchored in many of the same places Tuesday, potentially becoming more expansive across Pennsylvania and the northern Mid-Atlantic.
Increasing winds across the Midwest may cause a reduction in smoke by Wednesday, but high pressure hovering near the Northeast will keep smoke — and a campfire-like smell — locked in through at least Friday.
Western states
The largest active fires by size in the United States, according to the National Interagency Fire Center, are the White Sage fire near Fredonia, Arizona (58,985 acres) and the Monroe Canyon fire near Monroe, Utah (55,642 acres) as of early Monday.
Smoke from these fires is expected to spread eastward in Colorado, southern Wyoming and northern New Mexico on Monday and Tuesday, blown by strong winds.
Meanwhile, the coverage of wildfire smoke will probably also expand across Southern California.
Elevated-to-critical fire weather risks cover several Western states from Monday into Tuesday. (Ben Noll/The Washington Post/Data source: NOAA/SPC)
The state had 16 active fires as of early Monday, according to the California Department of Forestry and Fire Protection. The largest fire, covering nearly 50,000 acres as of Monday morning, is the Gifford Fire. Mandatory evacuations are in effect for San Luis Obispo and Santa Barbara counties.
These strong winds, combined with locally record-breaking high temperatures, will raise the wildfire risk into the elevated-to-critical range for several Western states starting Monday.
How far the smoke will spread
A strong jet stream crossing the Atlantic will take wildfire smoke on a winding, 5,000 mile journey from the Canadian Prairies to Western Europe this week.
The smoke will be lofted well above the surface, so while it won’t affect air quality, it could enhance sunrises and sunsets from Ireland to Norway and Germany as it spreads into Western Europe from Tuesday to Thursday.
This is not the first time this year that smoke has spread across the Atlantic. In early June, Canadian wildfire smoke reached Russia.
Where the smoke is coming from
Dozens of out-of-control wildfires stretching from Canada’s Northwest Territories to western Ontario are the main source of the smoke blowing into the United States.
An air mass that was over central and northern parts of Canada last week has drifted into the Northern United States, dragging cooler air — and smoke — along with it.
Parts of Alberta, Saskatchewan, Manitoba and western Ontario in Canada, have experienced extreme levels of drought this year.
These tinder-dry conditions have contributed to wildfires that have burned through over 16.3 million acres so far this year — the third-highest on record, according to the Canadian Interagency Forest Fire Center.
There have been 247 large wildfires across Canada so far this year, including 165 burning on Aug. 4. (Ben Noll/The Washington Post/Data source: Canadian Interagency Forest Fire Center)
There have been a total of 247 large wildfires in Canada in 2025, with 165 out of control across several provinces as of early Monday. The largest number of large fires, 53, have occurred in Saskatchewan, followed by 47 in Manitoba.
While rainfall in the region with active fires has been especially sparse, storms later this week may bring much-needed moisture to the Prairies.