Forecasters at the National Oceanic and Atmospheric Administration (NOAA) have issued a warning that the polar vortex—a band of powerful stratospheric winds encircling the North Pole—is weakening unusually early and may disrupt within days, potentially sending Arctic air southward over North America and Europe.
In its latest November outlook, NOAA’s Climate Prediction Center stated that a sudden stratospheric warming (SSW) event, described as "very rare" for November, could develop. If this occurs, its effects may persist for up to two months, influencing weather patterns across the Northern Hemisphere. The agency noted that while the disruption’s impact on the eastern U.S. remains uncertain, it could compete with the influence of a strong El Niño, which currently favors milder conditions for much of the country.
What is the polar vortex?
The polar vortex is a large, swirling mass of cold air and strong winds located in the stratosphere, roughly 10 to 50 kilometers (4 to 31 miles) above Earth’s surface. It typically acts as a barrier, keeping frigid Arctic air confined near the North Pole during winter. When the vortex weakens or shifts, pockets of this cold air can break free and move southward, bringing sharp temperature drops and winter-like conditions to mid-latitude regions.
Potential impacts on North America
NOAA’s Jon Gottschalck, branch chief at the Climate Prediction Center, emphasized that while strong SSW events can trigger the chain reaction leading to cold air outbreaks, it remains unclear whether this specific disruption will do so. The agency’s graphic illustrating the vortex’s weakening underscores the complexity of predicting its downstream effects.
Historically, polar vortex disruptions have led to record-breaking cold. In January 2023, a lobe of Arctic air plunged into the eastern U.S. and Canada, with northern Minnesota recording -43°F (-42°C) on January 24. States like Indiana also experienced record lows, while Greenland’s west coast recorded its warmest January on record, highlighting the vortex’s global reach.
European outlook: Early snow risk for the UK
Across the Atlantic, British forecasters are warning of a similar early weakening of the polar vortex, which could allow cold Arctic air to push southward into the UK. Scientists note that if the vortex’s winds reverse direction by mid-November, the jet stream could shift, increasing the likelihood of cold, dry air settling over Britain. This could lead to blocked weather patterns and even early snowfall, according to Dr. Regan Mudhar, a weather scientist from the Université de Lausanne.
The Old Farmer’s Almanac has already released a long-range forecast predicting rain and mild temperatures in the Northeast U.S. alongside snow in the Upper Midwest ahead of Thanksgiving. However, major meteorological organizations like NOAA and AccuWeather have yet to release detailed holiday forecasts, with early outlooks suggesting warmer-than-normal conditions across the northern U.S. and rain in the South.
How El Niño complicates the forecast
The current strong El Niño—a warming of Pacific waters that influences global weather—is expected to counteract some of the cold air outbreaks by steering milder conditions over much of North America. NOAA meteorologist Laura Ciasto noted that the latest Week 3–4 outlook favors above-normal temperatures across the northern U.S. and California, aligning with typical El Niño impacts. However, the South and Southeast remain highly uncertain, as models have not yet converged on a clear signal for Thanksgiving week.
Travel implications ahead of Thanksgiving
With Thanksgiving less than three weeks away, holiday travel plans could be affected by shifting weather patterns. Last year, AAA predicted a record 81.1 million Americans would travel at least 50 miles from home during the holiday period, making weather disruptions a significant concern for road and air transportation. AccuWeather anticipates rain in the South and snow at higher elevations in the West, while NOAA’s uncertainty remains elevated for the South and Southeast.
Uncertainty and next steps
Forecasters caution that the polar vortex’s behavior is highly unpredictable, especially in early November when it is still strengthening. While SSW events typically occur later in winter, this early disruption raises questions about whether climate change is altering traditional atmospheric patterns. Scientists emphasize that further monitoring is needed to determine the full extent of the vortex’s weakening and its potential consequences.
For now, NOAA and other agencies will continue tracking the situation, with updated forecasts expected in the coming days as the situation evolves.