(CNN)Some northern states are bidding farewell to April with a blast of snow.
More than 15 million people from South Dakota to Michigan were under winter storm warnings or advisories Saturday morning, the National Weather Service said, with heavy snow and strong winds expected to bring hazardous travel conditions in parts of those states.
The fast-moving system could drop 2 to 8 inches of snow across the region from by Sunday morning.
Up to 6 inches of snow could accumulate in Chicago, where rain began changing to snow early Saturday afternoon.
"It's bringing us back to like January or February for some folks," said CNN meteorologist Allison Chinchar.
The snow is already making life miserable for some travelers, with Chicago's O'Hare International Airport indicating delays of more than 5 hours.
Hadley, Minnesota, had about 4 inches of snow as of Saturday afternoon, and Dubuque, Iowa, had 2 inches, CNN meteorologist Gene Norman said.
April snow isn't unheard of in the Upper Midwest. A couple of weeks ago, a major spring storm unloaded heavy snow and blizzard conditions from the Dakotas to Minnesota. Last year, a mid-April snowstorm brought a record 15.8 inches of snow to Minnesota's Minneapolis-St. Paul area.