Washington D.C. activated an Extreme Cold Alert on Thursday as overnight temperatures will be as low as 20 degrees with a wind chill. 

An Extreme Cold Alert occurs when the National Weather Service (NWS) predicts temperatures that will pose an immediate risk to residents. 

POLAR VORTEX: WHAT IS IT?

D.C. isn’t the only area experiencing frigid weather this week. Around 180 million Americans are in the middle of an arctic blast which is causing extreme freezing temperatures. 

As of Thursday, most of the country had record lows and is expected to set more tomorrow. 

Millions of Americans have already felt portions of this bitter arctic air from the Polar Vortex sweeping across the U.S.

When there is a disruption in the Vortex, it becomes weak and pushes colder air south towards Canada and the U.S.

On top of a La Niña winter, this has caused us to see typical temperatures for early February to appear in December.

ARCTIC BLAST USHERS IN FREEZING, POTENTIALLY RECORD COLD FOR 235 MILLION AMERICANS TO KICK OFF LA NIÑA WINTER

This new wave of Arctic air has already brought colder temperatures than what most of the country saw on Monday, where a Cold Weather Advisory was in effect for northern Montana and wind chills caused it to feel 20 to 30 degrees below zero. 

Many areas will stay at or below freezing, as the coldest air will linger over the High Plains and Upper Midwest, leaving cities like Chicago and Minneapolis to likely not climb above freezing for the duration of the week. 

CHICAGO BRACES FOR THE ARCTIC BLAST AND A SECOND SNOWSTORM

According to the FOX Weather Center, today into Friday, things take a bigger shift Thursday, as the weather pattern evolves, ushering in a stronger blast of colder Arctic air. The push is even more frigid due to the colder temperatures leading up to the big blast.

The Midwest is the focal point for the coldest temperatures today, with the widespread outlook readings between 10 and below zero, as portions of the region are already feeling -28 to -31 degrees due to wind chill this morning.

Iowa and Minnesota reign as the first record-breakers today, bringing in four record lows for the cities of Waterloo, Sioux City, Cedar Rapids and Hibbing. 

More potential records could also be broken for Des Moines, Cedar Rapids today.

By Friday, the heart of the cold will expand to the I-95 corridor, where more record lows may fall across cities like Pittsburgh, New York, Indianapolis and Baltimore. 

Morning temperatures across the Midwest and Great Lakes will be in the single digits, while the I-95 corridor will reach the upper 20s, making it 15 to 25 degrees below average for this time of year. 

HOW TO WATCH FOX WEATHER

In total, over 40 record low temperatures are possible across the Northern Tier for both today and Friday and below-average temperatures are expected to remain in some regions through mid-December.