Washington (United States) (AFP) – Meteorologists said they observed an exceptionally early disruption of the polar vortex on Friday, which increases the risk of cold waves across the northern hemisphere, although the consequences are still uncertain.

Published on: 06/11/2026 - 23:06

The polar vortex is a vast phenomenon of very powerful winds circulating between 10 and 50 km altitude above the Arctic during winter in the northern hemisphere.

Variations in its intensity and configuration (shape, temperature, etc.) can have consequences on the weather, leading, for example, to a significant drop in temperatures.

These winds strengthen in autumn until reaching their peak in January. The polar vortex can weaken in the second part of winter, usually between January and March, allowing extremely cold air to descend south and affect Europe, North America and Asia.

But according to scientists, the vortex is already weakening at the beginning of November.

- El Niño -

“To our knowledge, this is the earliest stratospheric vortex disruption ever observed,” Tim Stockdale and Frederic Vitart of the European Center for Medium-Range Weather Forecasts (ECMWF) told AFP.

The disruption of the vortex "considerably increases the risk of cold waves in the most populated regions of the northern hemisphere, the United States, Europe and East Asia", specifies Judah Cohen, a climatologist from the Massachusetts Institute of Technology, interviewed by AFP.

Such precocity “is exceptional”, adds Grahame Madge, spokesperson for the British Met Office. A possible explanation would be “the amplitude of the El Niño phenomenon in the Pacific” this year, he adds.

El Niño is a natural phenomenon that returns every two to seven years.

Surface waters in the central and eastern equatorial Pacific Ocean warm from spring onwards, leading to major changes in global wind, pressure and precipitation patterns in the following months.

This year, the phenomenon is exceptionally powerful.

For their part, Tim Stockdale and Frederic Vitart said they did not know where such an early disruption of the polar vortex came from, but also pointed to El Niño.

A disturbance in November has only been recorded three times since records began in the 1950s: in 1958, 1968 and 2025, all on November 28.

- Global warming -

As this disturbance occurs very early, its effects could however be "less marked" than when the disturbance occurs in the middle of winter, he adds. Because “the temperatures in the source regions of these air masses, such as Siberia or the Arctic, are not yet as low as they will be in February”.

According to Judah Cohen, El Niño, which tends to make winters milder, could also help. This could "moderate or modify" the impacts of an early polar vortex, although it remains uncertain.

At this stage, Météo France estimates that the consequences for the weather remain "very uncertain" in France, and "will depend on how the disturbance will evolve".

The phenomenon could "reinforce within several weeks" the temperature differences between the north and the south of Europe, with colder weather in the north and warmer in the south, adds the French agency.

Global warming may also play a role, according to Judah Cohen, although no studies have established a link.

burs-ia/eml/bpe

© 2026 AFP

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