Horrific summer wildfires are once again ravaging large swaths of Canada’s vast forests, sending frequent plumes of unhealthy smoke deep into the United States.
With fire danger at very high levels throughout much of Canada, we can anticipate that these major smoke-emitting fires will continue to burn for an extended period. Furthermore, the long-range fire forecast calls for above-average fire risk over much of the forested areas of western Canada and the Western U.S. this summer, and we should anticipate frequent bouts of poor air quality from wildfire smoke across much of North America.
Unlike the activity during the record Canadian wildfire season of 2023 – when wildfire activity was focused in the west (Alberta) and east (Quebec) – the fires in 2025 are also plaguing the central provinces of Saskatchewan and Manitoba.
Why are the Canadian wildfires so bad this year?
As the climate warms, fire danger increases, mostly because the atmosphere gets “thirstier” – more water vapor can evaporate into warmer air. This results in more water vapor evaporating from plants, which dries them out and creates an increased risk of large and intense fires that can generate huge smoke plumes.
The first major Canadian wildfire smoke event for the U.S. during 2025 invaded North Dakota on May 30. Between May 30 and June 4, portions of nine states – North Dakota, Minnesota, Wisconsin, South Dakota, Michigan, Nebraska, Iowa, Indiana, and Montana – experienced smoke that brought levels of fine particle pollution (PM 2.5, particles less than 2.5 microns in diameter) in excess of the 24-hour EPA standard of 35 micrograms per cubic meter. This corresponds to an Air Quality Index, or AQI, above 100 – in the “Unhealthy for Sensitive Groups” range (color-coded orange).
Portions of five states experienced 24-hour levels of PM 2.5 in the “Unhealthy” (red) range, with even higher levels – in the purple “Very Unhealthy” range – were measured on an hourly basis. According to the U.S. Environmental Protection Agency, at the red “Unhealthy” level, everyone may begin to experience health effects, and members of sensitive groups may experience more serious health effects.
As of Thursday, there were 202 active wildfires burning in Canada, with 109 of these considered to be “out of control,” according to the Canadian Interagency Forest Fire Centre. The fires had burned 6.4 million acres, killed two, forced over 26,900 people to evacuate, and destroyed at least 191 structures. The area burned is now the second-largest on record for this time of year, trailing only the record fire season of 2023.
As reported by the Hotshot Wake Up Substack feed, a very dry and windy airmass set up over Saskatchewan on Tuesday and “caused massive wildfires to run across the province. Entire communities were devastated. At one point, it was reported that HALF of Saskatchewan was without communications or internet due to infrastructure damage. The largest town in the northern part of the province was evacuated. The town of Denare Beach (population 700) was eviscerated after the Wolf Fire ran through the community. There are reports of over 164 structures lost and half of the town destroyed. Hospitals in the area received a CODE ORANGE alert indicating that they could receive a major influx of patients due to a disaster situation.”
The summer forecast: above-average fire risk over much of Canada and the Northwest U.S.
The latest seasonal fire forecast (Fig. 1) from the U.S. National Interagency Fire Center (with assistance from Canada and Mexico), predicts that there will be above-average fire risk over much of western Canada and portions of California and the Northwest U.S. during June. The area of risk is forecast to expand in July, with a separate area of above-average risk spreading from Texas into Oklahoma. The forecast for August and September (Fig. 2) warns of a further expansion of the above-average fire risk area over the Western U.S., with a continuation of the Southern Plains risk in August plus a new area in northern Minnesota.
The fire season so far in the U.S. has been near-average, with 1.1 million acres burned as of June 2 across the 50 states, according to the National Interagency Fire Center. That’s close to the 10-year average of 1.2 million acres. But with the summer fire season just beginning, and central Canada already experiencing near-record wildfire activity similar to that in 2023, the latest seasonal forecasts suggest that a long summer of wildfire smoke – similar to what we saw two years ago – may be in store for residents of the U.S. and Canada in 2025.
Read: Silent calamity: The health impacts of wildfire smoke
Read: How to protect yourself from wildfire smoke
Bob Henson contributed to this post.
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