Canadian wildfire smoke will again choke Minnesota skies on Sunday, prompting a statewide air quality alert that will last most of the day.

The air will be unhealthy for sensitive groups starting overnight Saturday through 11 p.m. Sunday, according to the Minnesota Pollution Control Agency. Residents with cardiovascular and respiratory conditions should avoid prolonged exposure to the smoke and limit heavy exertion outdoors.

The smoke should blow through quickly, and some areas may only suffer bad air for a few hours. But there's also the possibility another round of smoke finds its way south once skies clear Sunday night.

"The air quality alert may need to be extended into Monday if an additional batch of heavy smoke materializes from Manitoba and Saskatchewan wildfires and is transported into and across Minnesota from north to south, but confidence for this outcome is currently low to medium," the MPCA said in a news release.

Minnesota recently tied a poor air-quality record and has suffered several days of smoky skies this spring due to hundreds of forest fires in Canada, 78 of which remain uncontrolled. Shifting winds send the smoke south, while cold fronts bring the smoke closer to the ground.