Canada wildfire smoke may return to US this week. Here's where forecasters are watching.

Smoke from Canada's wildfires may return to the U.S. this week after plaguing parts of the East with widespread air quality concerns last week, forecasters warned.

AccuWeather satellite imagery showed smoke from Ontario flowing into the upper Midwest on Tuesday. Though the smoke may lead to air quality concerns, AccuWeather forecasters say, it won't be as intense as last week, when plumes of smoke turned skies orange and led to historically bad air quality levels in the East.

That's because the fires in Ontario, while numerous, are relatively small, said AccuWeather senior meteorologist Brett Anderson.

The smoke also isn't expected to stay long; storms and shifting winds are forecast to reduce the smoke in the U.S. by Friday, according to AccuWeather.

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Still, the upper Midwest, especially the eastern Dakotas through Minnesota, northern Wisconsin and upper Michigan, may see poor air quality "over the next few days," Anderson said.

Canada had 461 active fires as of Wednesday morning, and 236 were considered "out of control," according to the Canadian Interagency Forest Fire Centre. Ontario had 65 active fires.

The agency was at a national preparedness level of 5 on Wednesday, the highest level of wildfire activity response.

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This article originally appeared on USA TODAY: Canadian wildfire smoke may once again affect US air quality this week