This fresh wave of icy air is set to sweep across the Eastern U.S., potentially bringing the chilliest conditions yet this season, extending its reach as far south as Alabama.

“Regarding the cold snap expected in mid-December, I see the early December cold as just a precursor, with the main event arriving in mid-December,” explained Judah Cohen, director of seasonal forecasting at the Atmospheric and Environmental Research for the JANUS Research Group.

Cohen points to a stretched polar vortex as the culprit behind these successive cold spells.

“Typically, the polar vortex is a circular formation centered over the North Pole. However, it becomes stretched or elongated, affecting regions from East Asia to eastern North America,” he clarified.

This pattern allows Arctic air to spill much farther south, contributing to multiple outbreaks across the U.S. during the first two weeks of December.

NOAA’s Climate Prediction Center is forecasting another one. Its latest 6- to 10-day outlook shows a high probability of below-average temperatures for the Eastern U.S. from Dec. 12–16.

Click here to see the forecast from your trusted local weather team

The next blast of Arctic air is expected to arrive in the northern Plains and Midwest late this week before pushing into the East, Mid-South and South. In the Midwest, wind chills are forecast to plunge well below zero in cities including Minneapolis, Chicago, Kansas City and St. Louis. Low temperatures in Detroit are expected to drop into the single digits by the weekend.

Across the Mid-South, temperatures are forecast to fall into the low 20s and even upper teens. Farther south, much of northern Alabama could see wind chills in the teens.

However, Cohen said there are signs the cold won’t stick around through the end of December. 

“From what I can tell, the cold meal is clearly coming to an end after the third week of December, and I’m not even sure if the cold will hang around for dessert heading into the holidays,” he said. “The whole cycle that began at the end of November and will last until mid-December is clearly coming to its conclusion.”

The Climate Prediction Center’s outlook for late December also favors warmer-than-average conditions for most of the U.S.