An arctic air mass sprawling across the eastern, central and parts of the western U.S. on Monday will channel temperatures 20-30 degrees below already historically cold January averages and was poised to slam parts of the South with a disruptive winter storm.

Amid a dangerous arctic blast over much of the U.S. this week, snow and ice may bring major travel disruptions and power outages in the South, forecasters warned.

Most of the United States is being assailed with extreme winter weather this week as Arctic air blasts south from Canada, snow tracks up the Northeast coast and a potentially crippling winter storm takes aim at the South.

Arctic air is set to bring bone-chilling temperatures across much of the U.S. in the coming days, making for a far colder-than-average Inauguration Day. How cold will it get?

The inauguration of President-elect Donald Trump in Washington will be a cold one, the coldest since President Ronald Reagan's 1985 inauguration. MORE: Trump's inauguration will be coldest in decades That one also had to be pushed indoors due to brutal cold,