Key points: A sudden stratospheric warming above the North Pole is weakening — and may reverse — the polar vortex. Over the next 10–14 days this disturbance could allow Arctic air to reach the mid-latitudes, raising the chance of a colder, snowier December in parts of the Northern Hemisphere. The timing is unusually early for November and forecasts remain uncertain about where the strongest impacts will occur; scientists also warn that aging satellites and data gaps are making monitoring harder.
Polar Vortex on the Move: Sudden Stratospheric Warming Could Bring an Early Cold, Snowy December
Key points: A sudden stratospheric warming above the North Pole is weakening — and may reverse — the polar vortex. Over the next 10–14 days this disturbance could allow Arctic air to reach the mid-latitudes, raising the chance of a colder, snowier December in parts of the Northern Hemisphere. The timing is unusually early for November and forecasts remain uncertain about where the strongest impacts will occur; scientists also warn that aging satellites and data gaps are making monitoring harder.
11:24 PM, 11/19/2025Environment
High above the North Pole, the stratosphere is warming rapidly in a sudden stratospheric warming (SSW) that is weakening — and could even reverse — the polar vortex. Over the next 10–14 days, this disturbance may nudge Arctic air into the mid-latitudes and help establish a colder, snowier pattern for parts of the Northern Hemisphere in December.
What’s happening
Think of the stratospheric polar vortex as a circular wall of fast winds that confines frigid Arctic air near the Pole. When a sudden stratospheric warming occurs, that circulation can slow, weaken or reverse, allowing cold air to spill south into North America, Europe and Asia.
Why this matters
“This warming in the stratosphere is weakening the polar vortex winds, and they could even reverse,” said Amy H. Butler, a meteorologist at the National Oceanic and Atmospheric Administration. Scientists study SSWs because they can trigger strong surface cold-air outbreaks, sometimes weeks after the warming begins.
Timing and uncertainty
One notable aspect of this event is its timing: SSWs of this magnitude are rarely observed in November, said Judah Cohen, a research scientist at MIT. While the disturbance could contribute to a colder, snowier December in some regions, forecasters cannot yet pinpoint where the strongest impacts will occur. Once disrupted, the polar vortex can take a month or longer to recover, according to Andrea Lopez Lang, a meteorologist at the University of Wisconsin–Madison.
Typical patterns and potential impacts
Past early-season polar vortex disruptions have often produced a ridge of warmer high pressure over Alaska and a downstream trough in the jet stream across central and eastern North America. That configuration tends to steer colder air and increase snowfall potential over the Central and Eastern United States. Similar large-scale shifts can bring cold outbreaks to parts of Europe and Asia.
Observing challenges
Satellites are the primary way scientists observe the stratosphere and track developing SSWs. Lopez Lang warns that aging polar-orbiting satellites and program decisions that affect future measurements are reducing the continuity of critical data streams needed to monitor these events and improve forecasts.
Improved stratospheric observations and modeling can sharpen 7–10 day forecasts and help communities prepare for possible cold-air outbreaks. Researchers continue to monitor the evolving SSW and will update surface weather outlooks as the signal propagates downward.