CHICAGO —  Hundreds of airline flights were grounded Wednesday and a major league baseball game was called as yet another spring snowstorm spread wet snow across the upper Midwest.

North Dakota and South Dakota both measured about 7 inches, and up to 10 inches was possible in Wisconsin, the National Weather Service said.

"It's kind of flying sideways," hardware store owner Harvey Neu said in Menomonee Falls, Wis. "It's not like a gently falling snowfall. It's more of a get-out-of-my-face type of thing."

About 400 flights were canceled at O'Hare International Airport because of poor visibility, said city aviation spokesman Gregg Cunningham. The airport also had delays of one to 2 hours on both inbound and outbound flights, and delays at Midway Airport were about 30 minutes, he said.

"The storm system is moving north right now, but it may circle around and stay in the area," Cunningham said.

Milwaukee's General Mitchell International Airport also had a handful of delays and cancellations.

"I think we are all cranky about the weather," said Pat Rowe, spokeswoman for General Mitchell International Airport in Milwaukee. "We are ready to be done with winter, but that's the month of April in Wisconsin. ... There's really nothing that anyone can do besides book a flight to a warm location before the storm hits."

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Wednesday's Houston Astros at Chicago Cubs game was postponed because of the storm. During the weekend, heavy snow wiped out scheduled Angels-Indians games for four straight days at Cleveland, and their contest was finally moved to Milwaukee's enclosed field.

Nearly two dozen school districts canceled classes Wednesday across southern Minnesota, where up to 6 inches of snow was forecast. More closed in Iowa, where numerous vehicles had slid off slippery highways.

Snow this late is not that unusual, said weather service meteorologist Andrew Krein in Chicago.

"Typically every few years we'll get some snow in April," Krein said. "Snow in April is not unheard of."

Thirteen years ago, in fact, Sioux Falls, S.D., got 10 inches of snow on April 28.