Preparations are underway as an arctic blast dives into the nation's interior and southern regions and pushes a snowstorm into the Mid-Atlantic and Northeast that will be followed by lethal cold.

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.