Forecasters expect the polar vortex to break down in early November, weeks earlier than it ever has.
Weather models show the winds circling high above the North Pole slowing down and reversing around Nov. 4, which could split the vortex in two, Severe Weather Europe reported. The European ensemble gives that reversal a 96% chance. The American ensemble has it at 71%.
No major disruption has come this early since records began in 1959. The earliest so far happened on Nov. 28, in 1968 and again in 2025, according to polarvortex.earth, as cited by Capital Weather. This one would beat that by about three weeks.
“This will be, I think almost undoubtedly, the largest, earliest disruption of the polar vortex on record,” Judah Cohen, a research scientist at MIT, told Fox Weather.
What It Could Mean for the East
The polar vortex normally keeps the coldest air up near the Arctic. When it gets disrupted, some of that air can move south.
“We’re already seeing the polar vortex become distorted and stretched out,” Laura Ciasto, a meteorologist with the National Weather Service, told The Philadelphia Inquirer. She said these events “lead to increased probabilities of below-normal temperatures across the Eastern United States.”
The effects usually take a couple of weeks or more to reach the ground. The Inquirer reported that they could show up in the second or third week of November, possibly before Thanksgiving on Nov. 26.
After last year’s disruption in late November, the eastern U.S. had a colder-than-normal winter, according to Capital Weather.
Why It Might Not Turn Cold
The official forecast doesn’t show any cold yet. NOAA’s Climate Prediction Center favors above-normal temperatures across most of the country through Nov. 14. Only parts of the Southeast lean near or below normal.
El Niño is also in play, and it usually means milder winters for much of the U.S. “I’m thinking we may not see a response in North America,” Matt Rogers of the Commodity Weather Group told Capital Weather.
Ciasto said there have been so few of these events in November that “there’s some uncertainty about what the surface impacts might look like.”
Cohen said the same. “I don’t know what’s going to happen, and I don’t think anyone else does either,” he told Capital Weather.
In October, every major weather model already had the polar vortex heading for record-weak levels in early November. The latest forecasts show it breaking down altogether.
