SIOUX FALLS, S.D. >> A frigid blast of air is moving into the mainland U.S. thanks to a powerful storm that hit Alaska with hurricane-force winds over the weekend. Residents in the Upper Midwest are bracing for heavy snow and temperatures plunging across numerous states.

Here’s what to expect:

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WINTER IS … HERE

The storm is threatening to drop a foot or more of snow in Minnesota, Wisconsin and Michigan after pushing through Montana, Wyoming and the Dakotas, while also dropping thermometer readings by as much as 40 degrees below average.

Some school districts in Minnesota and South Dakota cancelled classes on Monday because of snow, while slick roads welcomed morning commuters in parts of Wisconsin. The National Weather Service said the wet, frigid weather is moving east, but to keep your coats handy: The plunging temperatures are expected to linger.

In Great Falls, Montana, the high temperature — typically in the low 40s this time of year — is predicted to be 7 degrees early this week and stay below freezing into the weekend. The forecast for Sioux Falls, South Dakota, is a high of 25, which is about 20 degrees below normal. High temperatures in Minneapolis will only reach the upper 20s.

“We’re kind of getting locked in winter’s grip here,” said Troy Kleffmen, a National Weather Service meteorologist in Aberdeen, South Dakota.

Residents in Minnesota should prepare for between 8 inches and 12 inches of snow, while Chicago also is expecting earlier-than-usual wintry weather. Weather service meteorologist Gino Izzi said the highs in the city are expected to settle into the 30s from Tuesday through Friday, while nightly lows could drop into the teens.

“It doesn’t look real promising for a warmup after that, either,” he said.

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WHERE’S IT COMING FROM?

The weather is part of a powerful system being pushed in by the remnants of Typhoon Nuri that hit Alaska’s Aleutian Islands with hurricane-strength winds over the weekend.

Although that storm didn’t do much damage in Alaska’s sparsely populated Aleutian Islands, forecasters say it’s anchoring a system will push an unseasonably frigid blast of air into the mainland U.S. and send temperatures plunging early this week.

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THE GOOD NEWS

Yes, there’s good news. Sort of.

The National Oceanic and Atmospheric Administration isn’t expecting a repeat of the 2013-2014 season. Federal forecasters predicted last month that this winter will be fairly average without a lot of extreme conditions such as last year’s Arctic influx from the polar vortex.

That doesn’t mean it won’t be cold, and other private weather forecasters are predicting a slightly cooler winter than NOAA. And, a reminder: NOAA didn’t predict the extreme low temperatures experienced last winter.

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READY. SET. WAIT.

If you’re flying in the coming days, expect delays. Delta Airlines says snow in parts of the Midwest may affect travel, including to and from Wisconsin and Minnesota. The airline recommends checking your flight status early and often.

Driving isn’t recommended in general in winter storm areas, especially in some remote areas of the Northern Plains, but if you must drive, be prepared; Have a full tank of gas, an emergency kit and exercise caution on slick roads with high drifts and low visibility.

Even though South Dakota rancher Roger Weiss lives 35 miles from the nearest town, Faith — with a population of less than 450 people — and 70 miles from a grocery store, in Sturgis, he said the coming snow generally doesn’t worry him.

“Roads are generally good, a lot of times they’re blowed clean,” Weiss said.