In the upper Midwest of the United States, Michigan, Wisconsin and Minnesota have issued air quality warnings as smoke from the Prairie wildfires is dragged south by a cold front. Those warnings expanded into the Northeast, causing some hazy skies.

Air quality reached "unhealthy" levels in North Dakota and small swaths of Montana, Minnesota and South Dakota, according to the EPA.

Online map tools and resources let you track the Canadian wildfires and monitor poor air-quality conditions, which are impacting US states.