What Is the Polar Vortex? Why It Sends Arctic Air South, per the NWS
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How we wrote this: A plain-English summary of National Weather Service guidance on the polar vortex, checked October 29, 2026.
Always there
The polar vortex is a large area of low pressure and cold air around both poles. It always exists. It weakens in summer and strengthens in winter. "Vortex" refers to the counter-clockwise flow of air that helps keep cold air near the poles.
Why it reaches the U.S.
Many winters in the Northern Hemisphere, the vortex expands, sending cold air south with the jet stream. The NWS says this happens fairly regularly in winter and is often tied to large outbreaks of Arctic air in the United States. The January 2014 outbreak was similar to earlier ones, including notable colder outbreaks in 1977, 1982, 1985 and 1989.
What it isn't
- Not new. The term became popular recently, but the feature has always existed.
- Not at the surface. Forecasters study it tens of thousands of feet up. The extreme cold we feel at ground level is linked to it.
How to prepare
The NWS says there's no cause for alarm, but be ready for colder temperatures:
- Check your forecast and dress for the cold; see wind chill and frostbite.
- At the start of each winter, check your home and car emergency kits.
- Watch for winter weather alerts, lake effect snow and ice storms.
Related: winter solstice 2026, snow squalls.