A new polar vortex is forming in the stratosphere above the North Pole, raising concerns about potential severe weather for the winter of 2025/2026.
Initial measurements show rapid drops in temperature and pressure across polar regions. Scientists caution that its development will play a decisive role in shaping winter weather across Europe, the United States, and Canada.
The polar vortex, which develops each autumn as the Arctic cools, largely determines whether a winter is mild or harsh. When strong, it traps cold air in the Arctic. When weakened or disrupted, frigid air masses spill southwards, triggering polar outbreaks and snowstorms.
For the coming season, forecasts indicate that the vortex is beginning weaker than usual. This coincides with other phenomena, including La Niña and the negative phase of the Quasi-Biennial Oscillation (QBO), both historically linked to sudden stratospheric warmings (SSW). These events weaken or even collapse the vortex, often leading to extreme cold snaps in Europe and North America.
Meteorologists note that early signals resemble last winter, when the vortex collapsed mid-season. If this scenario repeats, winter 2025/2026 could be particularly volatile, alternating between mild spells and sudden polar storms.
A new Polar Vortex is starting to emerge over the North Pole in the Stratosphere. Forecasts show it will have a harder time growing to full power, which increases the potential for a more dynamic Weather pattern in Winter 2025/2026https://t.co/nQ2vvgbqbj
— severe-weather.EU (@severeweatherEU) September 18, 2025
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