An arctic air mass will channel temperatures 20-30 degrees below already historically cold January averages. The South braced for a rare winter storm.

One to 3 inches of snow — and a small chance of up to 5 inches — could be ahead as the rare combination of freezing temperatures and moisture arrive in some areas of Florida this week, according to the National Weather Service Mobile.

More than 170 million people across the United States, from the Mexican border to the Canadian border are under cold weather alerts ahead of a crippling winter storm expected to sweep through the south from Texas to Georgia,