Polar vortex brings dangerously cold temperatures to most of the US

On January 22, 2025By Littum

A blast of arctic air from Canada has brought the coldest weather of the season to most of the United States. The system, known as a polar vortex, is expected to bring freezing temperatures to the Midwest, Mid-Atlantic and deep into the South.

And it looks like we could have more arctic blasts in the coming years.

Outbursts from the Arctic will continue across the Northern Hemisphere for decades to come, even as the region warms faster than the rest of the world, according to a study published in Environmental Research: Climate.

Strong gusts are expected from Montana to Nebraska this week, according to Accuweather. The freezing temperatures will move eastward and reach major cities like Philadelphia, where daytime temperatures will only reach the upper teens.

How the stratosphere affects the Earth’s surface climate

The polar vortex is a giant circular weather pattern in the upper atmosphere of the Arctic that surrounds the North Pole. It is a normal pattern that is stronger in winter and tends to keep the coldest weather bottled up near the North Pole.

The jet stream typically acts as a barrier to keep the polar vortex contained near the Arctic, but at times some of the vortex can break off or move south, bringing unusually cold weather into the United States, Europe, and Asia.

The image below shows how the influence of climate change from as far away as mid-latitudes can trigger a burst of Arctic air over the United States weeks to months later.

Can’t see our graphics? Click here to view them.

The polar vortex and the jet stream both extend south into the United States

NOAA’s Global Forecasting System model predicted that on January 16 the polar vortex would shift south of the tropospheric jet stream over North America, with the stretched polar vortex corresponding to the shift.

Where is the stratosphere?

Let’s investigate structure of the atmosphere. The troposphere, which extends up about 6 miles from the Earth’s surface, is the first layer of the atmosphere. The majority of our weather occurs here. The layer of the atmosphere that lies between 6 and 31 miles above the surface is known as the stratosphere. The polar vortex is inside the stratosphere.

Due to the lack of sunlight, both poles of the earth have significantly cooler temperatures than the equator. This means that the air at the poles becomes extremely cold and dense, causing a powerful jet stream to appear in the stratosphere and blow the cold air from west to east. This strong circulation is known as a polar vortex.

CONTRIBUTOR Anthony Robledo

SOURCE NOAA, Climate.gov, NASA and Royal Meteorological SocietyThis story was updated to add new information.