Temperatures plunged into the teens and single digits in some spots, and the snow-dusted winds are driving the wind chill below zero. The polar vortex, a swirling mass of Arctic air typically contained over the North Pole, has pushed south, driving bone-chilling temperatures into the eastern United States.

The polar vortex is a low-pressure system of cold air that swirls above Earth’s poles. There’s one over the South Pole in Antarctica – but for this story, we’ll be focusing on the one above the North Pole. Over the North Pole, the wind flows counterclockwise in the stratosphere around 16 to 50 kilometers (10-30 miles) high.

A new blast of Arctic air sweeping from north to south will bring bone-chilling temperatures to millions of Americans this weekend and next week.

A blast of Arctic air is set to cover much of the United States with temperatures below freezing starting on Friday and into next week, impacting millions of Americans in nearly all of the contiguous states.

However, a deep freeze, thanks to the polar vortex dipping down from Siberia, is about to bring even harsher arctic blast to nearly 300 million Americans starting this weekend. Maps show where and when the cold front will arrive.

Snow and winds are likely to disrupt traffic, trigger flight cancellations, and cause headaches for people traveling to D.C. for Inauguration Day. Baby, it’s cold outside, and it’s about to get even colder for much of the United States.

A major cold blast is in store for millions of Americans as a lobe of a polar vortex will bring brutally cold temperatures to nearly every American east of the Rockies.