Earlier, weather reports said snow would cover the Great Lakes and the Northeast ahead of an expected dip into Arctic-cold temperatures.
The wintry weather mostly moved out of the Plains overnight, pushing further into Wisconsin, Illinois and Indiana.
The National Weather Service said Chicago would see an additional 7cm-13cm Sunday.
The city's aviation website said more than 1200 flights had been cancelled at O'Hare and about 160 at Midway as of Sunday morning (US time).
Reports said Detroit could see the heaviest amount of snow Sunday, about 20cm. To the east, Cleveland could see up to 15cm, while Burlington, Vermont, could get up to three.
The Ohio River valley and Mid-Atlantic will see a mix of snow, freezing rain and rain.
Temperatures 15 to 30 degrees below average will follow the cold rain and snow in the coming days through much of the Midwest and East.
- AP
