This Halloween looks to be more frigid and frosty than frightening across parts of the country.

The National Weather Service's Weather Prediction Center said a strengthening storm system is moving in from Canada, bringing a surge of arctic air and heavy snow into the northern Rockies on Tuesday and across the Plains states. While up to a foot of snow is forecast to fall in parts of Colorado, up to up six inches of snow could accumulate by Halloween morning in parts of the Midwest.

"A lot of snow for parts of the Plains states Wednesday and Thursday, and then it’s going to make for a very wet Halloween for the eastern third of the country,” Fox News Senior Meteorologist Janice Dean said on "Fox & Friends." "A lot of weather to watch.”

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Heavy snow was already falling across the Denver area on Tuesday, with hundreds of flights either delayed or canceled at Denver International Aiport due to the storm, according to FOX31.

Forecasters said beside the heavy snow, winds are expected to pick up across Colorado on Tuesday bringing blowing snow with wind chills as low as 25 degrees below zero in some areas.

By Wednesday night, much of the snow will move east into locations such as the Kansas City metro area, stretching into Iowa and southern Wisconsin, where up to half-a-foot could accumulate into Halloween morning.

"This is no joke, as a winterlike storm has the potential to put down a swath of heavy snow over a 750-mile long swath of the Heartland prior to the end of this week," AccuWeather Senior Meteorologist Alex Sosnowski said.

After the storm passes, bitterly cold temperatures await trick-or-treaters in the Rockies through the Midwest. AccuWeather says that RealFeel Temperatures will fall into the 20s, teens, and single digits in the northern and central Plains and into the Great Lakes region by Halloween night.

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As the storm system moves east, it is expected to bring rainy conditions from the Gulf Coast all the way to the Northeast. The heaviest rain is forecast to fall Thursday night over the Appalachians from northern Georgia through western Pennsylvania and into western New York.

The big cities in the Northeast may miss out on the heaviest rain until the late-night hours, but conditions may still be damp and dreary throughout the day.

While it may be rainy, temperatures are forecast to be a little warmer than normal for the end of October with highs in the 70s through Virginia, and into the low-60s through New England.

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Once the cold front and storm system passes, conditions are expected to improve for much of the country by the weekend.