East-central Minnesota, including the Twin Cities metro area, will be under an air quality alert from noon to 9 p.m. Friday.
According to the Minnesota Pollution Control Agency, the expected sunny, hot weather combined with low humidity and light winds will lead to the formation of ozone.
Ozone, produced by the combined emissions of nitrogen oxide and volatile organic compounds, will be lowest Friday morning, gradually rise midday and peak in the late afternoon.
The unhealthy air can affect those with respiratory impairments; children and teenagers; anyone doing doing extended or strenuous physical activity outdoors; and otherwise healthy individuals who are more sensitive to ozone.
The air quality will improve by Friday evening.
Meanwhile, the National Weather Service says much of northern and western Minnesota will be under wildfire watches and warnings on Friday.
Temperatures approaching 100 in some locations of the region, gusty winds and low relative humidity will lead to conditions conducive to wildfire.