Forecasters are watching a rare atmospheric showdown that could affect winter weather across the United States and Europe. For the first time on record, the polar vortex – the high‑altitude band of strong winds that normally traps Arctic air over the North Pole – has begun to weaken in November, while a powerful El Niño is pushing global temperatures upward.
What the polar vortex and El Niño are doing
The polar vortex forms each fall as the Arctic night deepens, keeping frigid air locked aloft. When a major sudden stratospheric warming event occurs, the vortex’s winds can reverse, allowing cold air to spill southward. This year, researchers observed a dramatic warming in the stratosphere that has already caused the vortex’s winds to weaken, a phenomenon usually seen between January and March. The earliest comparable event on record happened on November 28 in 1968 and again in 2025.
At the same time, a historically strong El Niño is developing in the tropical Pacific. El Niño typically drives warmer global temperatures, acting like a “big bully” that can dominate the atmospheric flow. Some studies suggest a strong El Niño may weaken the polar vortex, but scientists caution that the exact interaction is still uncertain.
Short‑term impacts
North America and northern Europe are already feeling the effects. A surge of Arctic air moved across the eastern United States and parts of western Europe on Wednesday, bringing frost and temperatures 7 to 14 °F below mid‑November averages for many locations east of the Mississippi River. The cold snap is expected to peak on Thursday or Friday before giving way to above‑average warmth later next week.
While the current chill is not projected to be extreme, it represents a sharp contrast to the unusually warm fall weather many regions have experienced. Residents in the eastern U.S. and the United Kingdom should be prepared for a brief period of frost, especially in areas that have not yet seen winter conditions this season.
What’s next?
Experts say this early disturbance may be just the “appetizer.” The full impact of the polar vortex disruption could take several weeks to filter down, potentially bringing additional cold spells to eastern North America and northern Europe in late November or early December.
MIT climatologist Judah Cohen notes that the strength of the upcoming weather patterns will depend on how the polar vortex behaves after this event. If the vortex re‑strengthens quickly, the cold may be short‑lived; if further disruptions occur, more significant winter weather could follow.
NOAA research physicist Amy Butler adds that the dominant influence of the strong El Niño may keep temperatures warmer across much of the northern United States, even as occasional cold bursts arrive. The interplay between these two forces makes the coming weeks a valuable “experiment” for atmospheric scientists.
Bottom line for residents
Prepare for a brief cold spell this week, especially if you live east of the Mississippi River or in northern Europe. Keep an eye on local forecasts for any updates on frost advisories, and be ready for a quick return to milder temperatures as the El Niño continues to shape the season’s overall warmth.
Original reporting: KRDO (Colorado Springs metro) — read the source article.
