The polar vortex's blast of Arctic air from Canada brought the season's coldest weather to the majority of U.S. The vortex is forecast to provide frigid weather as it continues to bring sub-zero temperatures to the Midwest, Mid-Atlantic and plunge deep into the South.

An arctic blast will send temperatures across the United States plummeting as bitterly cold air that originated in Siberia will arrive from Canada by week’s end, bringing with it dangerously cold wind chills for millions of Americans.

How the Polar Vortex Can Bring Arctic Blasts to the U.S. Vast weather patterns can carry blasts of frigid air far from the polar regions—here’s how it works

Most of the U.S. will enjoy milder temperatures on Thursday, but the warmup will be brief as a polar vortex will send temperatures tumbling below freezing for most of the nation starting this weekend.