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.

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.

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.

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.

Here's a detailed forecast and timeline of when NYC will see snow on Sunday, how many inches to expect and what's forecast to happen when a polar vortex sweeps the area next week: WARNING: This story contains details of intimate partner violence and may affect those who have experienced it or know someone who has.

"Once the snow starts to come in, the temperature will essentially drop like a rock," Fox Forecast Center Meteorologist Marissa Lautenbacher told The Post.

A dangerous and potentially life-threatening stretch of cold weather has much of the U.S. on alert as a lobe of the polar vortex invades the nation and sends temperatures tumbling to levels not seen in years.