Polar Vortex Set to Cause Dramatic Weather Change

United States (Brussels Morning Newspaper) – The polar vortex is undergoing a rare early stratospheric warming event that is disrupting its structure, leading to a dramatic shift in weather patterns. This will bring intense cold, snow, and unsettled conditions across North America and Europe this winter.

The Polar Vortex and the Unusual Stratospheric Warming Event

The polar vortex is a band of strong winds high in the atmosphere around the Arctic that normally confines frigid air to polar regions. This year, as reported by meteorologists on Severe-weather.eu, the vortex is experiencing a rare and powerful stratospheric sudden warming (SSW) event the earliest of its kind in 70 years. This warming in the stratosphere, located about 30 kilometres above Earth’s surface, is causing the polar vortex to weaken, slow down, and deform due to a large high-pressure anomaly compressing the vortex.​

Amy H. Butler, meteorologist at the National Oceanic and Atmospheric Administration (NOAA), explains that the warming leads to the weakening, and potentially reversal, of vortex winds, meaning the cold Arctic air can escape southward into lower latitudes. Such disruptions in the stratosphere often trigger severe cold outbreaks and snow events at the surface.​

Impact on North America

Across North America, this disruption is expected to bring a marked shift from recent warmer-than-average temperatures to periods of severe cold and snowfall. CNN’s weather report highlights that over the next 10 days the changes in the stratosphere will begin influencing surface weather, setting the stage for a cold and snowy December in the US, with potentially long-lasting cold spells.​

Severe-weather.eu predicts winter 2025/2026 will be colder than previously expected, with heavy snow and cold outbreaks affecting large parts of the US and Canada. The polar vortex weakening will make it easier for Arctic air to spill southward, particularly impacting the Northern Plains, Midwest, and parts of the eastern US.​

Effects on Europe

Western Europe is also bracing for the consequences of the polar vortex disruption. According to Severe-weather.eu’s report, a cold Arctic blast will spread from the UK and Ireland through France, Spain, and further into the continent. This pattern is supported by blocking high-pressure systems over Greenland and the North Atlantic, facilitating the cold air’s flow from the Arctic southwards.​

The increased cold will bring snowfall even to areas unaccustomed to early winter snow, affecting the UK and parts of southern Europe in the months ahead. This early winter pattern contrasts with recent mild winters and signals more persistent, colder weather affecting millions.​

The Mechanics Behind the Disruption

The stratospheric sudden warming event causing this disruption is quite rare at this time of year. Forecasters note that such early SSWs have only been recorded a handful of times in the past 70 years, making this one historically significant. The warming is linked to atmospheric waves breaking in the stratosphere, creating an easterly wind component that disrupts the vortex’s usual westerly flow.​

This disruption causes the vortex to wobble and sometimes split, diminishing its ability to keep cold air locked at the pole. The jet stream at lower levels becomes more erratic, favoring the southward movement of cold air masses and setting up conditions for severe winter weather.​

Predictions and Outlook for Winter

Meteorologists from various sources agree winter 2025-2026 will be notably colder and snowier due to this polar vortex disruption combined with ongoing La Niña effects in the Pacific, which can amplify cold conditions in parts of the Northern Hemisphere.​

Forecasters warn that this polar vortex event