A polar vortex dipping down from Siberia will bring a cold front with frigid temperatures to nearly 300 million Americans. See maps of the arctic blast.

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.

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