A collapse in the polar vortex is letting Artic air come here. What that means, and why it happens.

Much of the nation east of the Rocky Mountains is hunkered down for what could be the worst winter storm of the season.

As the U.S. prepares to take on another bout of cold weather, the term "polar vortex" is getting thrown around. But what is ...

Meteorologists warn that a stretched polar vortex could bring severe winter weather to much of the United States.

Rising Arctic temperatures and melting sea ice could be causing cold air to flow into the Northern Hemisphere. But not all ...

A winter storm descending on the US is expected to deliver heavy snow and ice to more than 150 million people across roughly ...

The meteorologists said the polar vortex system is set up due north of Michigan over Canada's Hudson Bay. It's at least ...

Similarly, wind chill temperatures measure how cold people and animals feel when outside, measuring the rate of heat loss ...

The sudden blast may come as a shock to many Americans after a mostly mild start to winter, but that warmth may be partly ...

After this weekend's snow storm moves out, cold Arctic air will move in.

Temperatures could fall below -20 F across certain parts of North Dakota and Minnesota.

Tens of millions of people are in the path of a major winter storm. Federal cuts threaten efforts to understand the causes of such weather.