The polarvortex.earth dashboard, which visualizes ECMWF modeling, currently shows a full breakdown of the vortex — the point at which its westerly winds turn easterly — by Nov. 20, according to phys.org.

Meteorologists said Friday they were observing an unprecedented early disruption of the polar vortex, which normally strengthens through autumn and peaks around January.

Weakening in early November, rather than in the typical January-to-March window, raises the risk of cold snaps across Europe, North America and East Asia, though forecasters stress significant uncertainty remains about how it will unfold.

A November sudden stratospheric warming has happened only three times in records dating back to the 1950s — in 1958, 1968 and 2025 — and all three occurred on Nov. 28, phys.org reports.

Scientific American notes that before now, the earliest such event ever recorded was Nov. 28 in 1968.

"As far as we know, this is the earliest stratospheric vortex disruption that has been observed," ECMWF principal scientists Tim Stockdale and Frederic Vitart told AFP, and France's Meteo-France called the event "unprecedented."

Scientists disagree on what triggered the earliness.

phys.org reports that Grahame Madge of Britain's Met Office said the earliness could be triggered by the amplitude of the exceptionally strong El Niño in the Pacific, while Stockdale and Vitart agreed El Niño "could have been a factor in making it more likely."

But climatologist Judah Cohen of MIT was more circumspect, telling AFP the disruption appeared more linked to a record-breaking high-pressure system over Scandinavia and northwestern Russia, a pattern more favored in La Niña years.

Cohen explained that Rossby waves surging upward from the troposphere trigger the sudden stratospheric warming that weakens or reverses the vortex's winds.

A weakened vortex can spill bitterly cold Arctic air south toward densely populated centers in the U.S., Europe and East Asia. Scientific American reports the experts describe the mood vividly: "Everybody's hair is on fire in the climate or meteorologist community," Cohen said.

For Britain, the Met Office's Marco Petagna told the PA News Agency that a wind reversal would make this a "major sudden stratospheric warming" event, potentially the earliest ever recorded, increasing the chance of cold weather deeper into November — though he cautioned a major warming last November did not directly lead to much UK cold.

Mitigating factors exist too: phys.org reports Madge noted Siberia and the Arctic are not yet as cold as they will be later in winter, and El Niño tends to bring milder winters that could "moderate or modify" the impacts.

Forecasters will monitor the vortex over the coming weeks to see whether the disruption propagates down to the lower atmosphere, which determines whether surface cold actually materializes.

phys.org reports Meteo-France said potential consequences for France remain "highly uncertain," depending on how the disruption evolves and its positioning. Scientific American adds that this could end up a "minor" event everyone forgets, or a "major" one that goes in the record books.

On the climate link, Cohen suggested rapid sea ice loss around Scandinavia and heavier snow in East Asia could be sharpening the Eurasian temperature contrast and amplifying Rossby waves — but he stressed that this is speculation, with no research yet confirming it, according to phys.org.