Wildfire smoke to limit number of days with deep blue sky this summer in Northeast, Midwest
Sunny summer days may not be quite as bright this year as smoke from wildfires burning across Canada occasionally spreads across the United States, resulting in hazy conditions and poor air quality.
Wildfires can produce smoke that impacts the air in areas thousands of miles away from the actual fire and can have a major impact on weather forecasting. AccuWeather’s Ariella Scalese explains.
Massive blazes erupted in Manitoba, Saskatchewan, Alberta and British Columbia much earlier than normal this year, and the wind has blown the smoke across Canada and into parts of the central and eastern United States. The result has been worsening air quality, including the first week of June when it reached "dangerous" levels in the Midwest.
AccuWeather Lead Long-Range Expert Paul Pastelok said long-lasting stretches of deep blue sky may not return to the Midwest and the Northeast for weeks or possibly even months, once fires burning in Canada are contained and extinguished.
During much of the summer, wildfire smoke will be high-flying in the atmosphere and can dim or even block the sun. When the sun is dimmed, it can help reduce high temperatures by a few degrees during the day and keep temperatures somewhat elevated at night.
Sunrises and sunsets may also be enhanced by the smoke and can even cause the sun to look red.
As the wildfire season across the western United States ramps up, new fires can pour even more smoke into the sky, contributing to the hazy, milky conditions.
A person watches the sunset, reddened by smoke from distant wildfires, from a park Sunday, June 1, 2025, in Kansas City, Mo. (AP Photo/Charlie Riedel)
The biggest impact on human health will be when the smoke dips to the lower levels of the atmosphere, degrading air quality and making the air smell like a campfire. The areas closer to the wildfires will have a higher risk of air quality impacts.
“On sunny days, especially when there’s consecutive sunny days in a row with a light wind, smoke and haze in the atmosphere can be more easily broken down by the sun and sink towards the surface, which can lead to a higher frequency of ozone action days or air quality alert days,” AccuWeather Meteorologist Brandon Buckingham warned.
Wildfire smoke contains fine particulate matter, aerosols and other contaminants, which can absorb and scatter ultraviolet radiation, leading to lower UV index readings at the ground level.
Despite a reduction in UV exposure and a drop in afternoon high temperatures in areas impacted by wildfire smoke high in the sky, experts say it’s important for people to apply sunscreen to protect their skin from harmful UV rays that can still reach the surface.
A hazy sky due to smoke from wildfires in Canada are seen over Lake Champlain and the Adirondack Mountains on Wednesday, June 4, 2025, in Burlington, Vt. (AP Photo/Amanda Swinhart)
“The closer you are to the fire, the higher the probability to be affected. But, of course, edge cases exist. You may be close to a fire and not be impacted at all, depending on the wind and the altitude,” AccuWeather Lead Wildfire Smoke Expert Dr. Boris Quennehen said.
“Smoke from wildfires can be transported across large distances, even near the ground level, and impact remote locations," Dr. Quennehen added.
Latest on the Canadian wildfires
Over 7 million acres of land across Canada have been scorched by wildfires so far this year, well above the historical average of 1.83 million acres for early June.
More than 74 fires are burning across British Columbia. There are 60 fires in Alberta, and dozens of other fires are burning throughout Manitoba, Ontario, Saskatchewan and the Northwest Territories.
Upcoming weather conditions across Canada could contribute to fires growing even larger or new fires breaking out.
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