ABC News December 31, 2024

Polar vortex 2025: Extremely cold temperatures headed to the eastern US

WATCH: What is the polar vortex?

Multiple rounds of frigid, arctic air could sweep across the eastern half of U.S. in the coming weeks, ushering in an abnormally cold start to 2025.

The first blast of bitter cold hits the Northern Plains and the Midwest on Wednesday and Thursday and then reaches the Northeast by the end of this week.

The surge of arctic air will likely be the start of multiple back-to-back cold blasts lasting throughout much of January, unleashing freezing temperatures across a large swath of the country.

Temperature Outlook - Jan. 7-13, 2025 Map
MORE: Follow New Year's Eve 2025 celebrations around the world

Beginning next week, the polar vortex will likely trigger even colder air across the eastern half of the U.S.

The polar vortex lives in the upper atmosphere and is located near the North Pole in the arctic. When the polar vortex is strong, it locks the cold air in the arctic. When the polar vortex gets weaker, or breaks up, it unleashes cold air to the south.

Selcuk Acar/Anadolu via Getty Images
People bear the cold in New York City, December 23, 2024.
MORE: New Year's Eve weather: What to expect

Temperatures will likely be below average throughout most of January for the eastern half of the U.S., especially the East Coast.

It is too early to know exactly how cold it will get, but there could be dangerously freezing temperatures for millions.

Spencer Platt/Getty Images
People enjoy a snowy morning in Prospect Park on December 21, 2024 in the Brooklyn borough of New York City.
MORE: How to stay safe in the cold

With the surge in cold temperatures, odds favor more precipitation falling as snow rather than rain in many spots.

A large, fast-moving storm may bring snow to parts of the Midwest and severe thunderstorms to the South early next week. Some of that snow may reach the mid-Atlantic, as well.