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

Temperatures will hover in the single digits above and below zero across the Front Range and Eastern Plains, but overnight wind chills will make it feel as cold as minus 30.

A Yellow Alert remains up through Wednesday for bitterly cold air and dangerous wind chills at times. Much of the Rochester region picked up accumulating snow from Lake Ontario Sunday night into Monday morning,

The coldest weather of the winter is here and won’t relent until late this week. Highs may not escape the 20s until Friday; on Wednesday, they may not surpass the teens. While it’s cold, it’s dry. Significant snow is not in the forecast this week. By the weekend, temperatures will start to moderate some.

GREEN BAY - Extreme cold weather hit the Green Bay area Monday morning with subzero temperatures and wind chills reaching minus 27. The extreme cold will last through Tuesday before warming up Wednesday, the National Weather Service said.

The 7 a.m. wind chill values were in the 30s and 40s below zero throughout Minnesota, including -35 in the Twin Cities. When you zoom out to see more of Minnesota and the entire region, it reveals the expansive area of Siberian air that has been spun south by a stretching polar vortex.