In Simple Terms
A powerful ring of wind high above the Arctic has weakened unusually quickly, and forecasts suggest it could briefly blow in the opposite direction in November. That may influence weather patterns later, but it does not mean widespread snow or a major cold snap is on the way. Scientists are still watching to see whether the wind actually flips and whether the change reaches the weather we feel on the ground.
A Sharp Drop in Wind Speed
Data from NASA Ozone Watch’s GEOS-FP series show how quickly the winds have weakened. On October 25, 2026, the average daily wind speed at 60 degrees north and the 10-hectopascal pressure level was 22.13 meters per second, or 49.5 miles per hour. Eight days later, on November 2, it had fallen to 5.44 meters per second, or 12.2 miles per hour.
The winds lost roughly three-quarters of their speed during that period. That does not mean they had stopped: they were still blowing from west to east, but much more weakly. The drop stands out when compared with the climate record shown by the same data series. The long-term average for this date from the 1978/79 season through the 2025/26 season is 25.62 meters per second, or 57.3 miles per hour. The lowest earlier reading recorded for November 2 was 13.68 meters per second, or 30.6 miles per hour.
So the November 2 reading was not only well below the usual average; it also fell below the previous lowest value shown for that date. Still, it is important to distinguish an observation from a forecast. The data confirm that the winds have weakened, but measurements analyzed through November 5 had not yet confirmed that they had reversed direction.
What Is Disrupting the Polar Vortex?
The polar vortex is not a separate object. It is a large-scale circulation of cold air above the Arctic. Strong westerly winds usually surround it, helping to keep the coldest air relatively close to the polar region. But large atmospheric waves rising from lower layers can interact with the circulation, stretching or shifting it and weakening the winds around it.
On November 4, the UK Met Office described the vortex as unusually elongated and pointed to strong activity from two atmospheric waves pressing on it from opposite sides. This coincided with rising temperatures above the Arctic, while forecasts suggested that the vortex could move farther from its usual position. That does not mean the Arctic has become warm in the everyday, ground-level sense. The temperature change is happening high in the atmosphere, where warming can weaken the circulation around the region.
The broad picture is consistent across several forecast models, but they differ on the details of the vortex’s path and how long the changes might last. Some forecasts from the European Centre for Medium-Range Weather Forecasts ensemble showed a chance that average wind speeds could briefly dip below zero during the second week of November. The UK Met Office described the possible reversal as relatively short and weak, and said it was still uncertain whether conditions would meet the criteria for a major event.
When Does a Weakening Count as a Major Stratospheric Warming?
The U.S. National Oceanic and Atmospheric Administration (NOAA) uses a specific standard to identify a major sudden stratospheric warming, or SSW. A slowdown in the winds is not enough, nor is a rise in temperature high in the atmosphere by itself. The key requirement is for the average daily wind around the 60-degree-north latitude circle, at 10 hectopascals, to switch from westerly to easterly sometime between November and March.
This distinction matters when interpreting forecast headlines. The reading of 5.44 meters per second on November 2 showed a substantial weakening, but it remained positive, meaning the wind had not yet reversed. NASA Ozone Watch’s series forecast that values might turn negative between November 9 and 11, which would indicate a shift to easterly winds. The series then forecast a return to westerly winds on November 12, making the anticipated reversal brief if it occurs.
NOAA also has rules for deciding where one event ends and another begins in its record of warmings. The winds must return to a westerly direction for 20 consecutive days between events, and they must remain westerly for at least 10 days before April 30. These rules help prevent closely spaced fluctuations from being counted as separate events and allow different seasons to be compared using a consistent method.
According to NOAA’s guide, which covers reanalysis data through 2023, one November event occurred on November 30, 1958, according to the NCEP-NCAR analysis. The guide lists another event in November 1968, although its start date varies from November 27 to 29 depending on the reanalysis product used. If a reversal in the second week of November 2026 is confirmed and meets the criteria, it would occur more than two weeks earlier than the November events listed in that guide. This comparison refers to that specific record; it does not claim to cover every historical observation that may exist.
A Significant Forecast, Not a Settled Outcome
U.S. outlooks shifted slightly between the end of October and the start of November. In its discussion of the week 3–4 forecast, issued by the U.S. Climate Prediction Center (CPC) at 19:00 UTC on October 30, the center described the situation as a rare November disruption of the stratospheric vortex. Guidance available at the time pointed to a possible transition toward a major warming in about a week and a tendency toward a negative phase of the Arctic Oscillation.
But the monthly outlook the center issued at 19:00 UTC on October 31 was more cautious: a transition to a sudden warming event remained a possibility during the following week, not a confirmed outcome. Changes in circulation linked to these events can continue to have effects for as long as two months, but their duration and consequences vary from case to case. A scenario appearing in some forecast ensemble members should not be treated as settled simply because it has been forecast.
The Arctic Oscillation is a broad pattern describing differences in pressure and circulation between polar regions and the mid-latitudes. In some cases, its negative phase has accompanied changes that help cold air move south into certain areas. But it is not a switch that controls the weather on its own. A signal pointing to a negative phase does not automatically reveal which regions will be affected, when the effects will arrive, or how strong they will be.
Why This Does Not Mean Widespread Cold Is Coming
The story begins in the stratosphere, a layer above the one where most everyday weather takes place. For a disturbance there to affect conditions at the surface, its influence has to move down into the troposphere. That transfer may happen, weaken, or be delayed, and other weather patterns can intervene. A wind reading at 10 hectopascals alone cannot tell us whether a particular city will get snow or a hard freeze.
The UK Met Office estimates that any downward influence from the stratosphere typically emerges over about two to six weeks. That is a broad window, and it does not mean the influence will definitely reach the surface or take any one particular form. In Europe, a major warming would raise the odds of a later change in circulation patterns, but it would not provide a definite forecast of cold or snow. What happens would depend on whether the disruption moves into lower layers and on the weather patterns in place when it gets there.
A 2026 assessment review by Environment and Climate Change Canada says that weather patterns following these events often resemble the negative phase of the North Atlantic Oscillation and may be associated with warmer-than-usual conditions in eastern Canada. This helps explain why the response is not the same everywhere: the same signal can be linked to different conditions in different regions, depending on the position of pressure centers and the paths of the winds at the time.
U.S. Outlooks Face Competing Signals
The CPC said the possible warming and negative Arctic Oscillation phase add uncertainty to the outlook for the start of winter in the United States. These factors may compete with patterns linked to El Niño, particularly in the eastern part of the country. In its ENSO discussion issued on October 8, the center said El Niño was continuing to strengthen, with a greater than 83% chance that a strong to very strong event would persist from January through March 2027.
Even so, the seasonal outlook issued on October 15 did not turn the possibility of a stratospheric event into a broad signal for cold weather. It favored above-normal temperatures across large areas, including eastern Alaska, the northern tier and western third of the contiguous United States, southern Florida, the Ohio Valley, and the Mid-Atlantic region. The outlook for November 14–27 also maintained enhanced odds of above-average temperatures along much of the West Coast and the northern tier.
In other words, the center sees the vortex disruption as one factor among several, not a standalone signal that overrides everything else. Even if the winds reverse, the outcome will depend on how that pattern interacts with El Niño and atmospheric circulation in the following weeks. For that reason, the CPC did not present the possible event as evidence that a widespread cold snap is approaching the United States. Nor did the agencies cited here forecast a cold surge across all of Europe.
What to Watch in the Coming Days
The first thing to check is whether the analyzed average wind at 60 degrees north and 10 hectopascals actually turns negative, rather than relying on model forecasts alone. Then come the next questions: How many days will the reversal last? Will the westerly circulation return quickly, as NASA Ozone Watch’s November 12 forecast suggests? And will signals from the stratosphere move far enough into the troposphere to change weather patterns at the surface?
It is also worth comparing the forecasts with what happens afterward. Some members of the ECMWF model ensemble may point to a reversal scenario, while the UK Met Office describes the possible event as limited and short-lived. These different levels of confidence do not necessarily mean the forecasts describe different phenomena. They reflect how difficult it is to tell whether the weakening will cross the threshold, how long a reversal might last, and whether it will persist long enough to leave a detectable mark on lower-level weather.
The comparison with the 1958 and 1968 events is useful for putting the timing of a possible November 2026 event in context. But the record in the guide is based on reanalysis data through 2023 and uses specific rules for selecting events. The comparison should not be stretched into a sweeping claim about everything ever observed. The strongest evidence in this story is the measured numbers and the unusual timing suggested by that particular record—not a claim that an absolute all-time record has been set.
The Bottom Line
Wind speeds in the polar vortex fell from 22.13 meters per second on October 25 to 5.44 meters per second on November 2, 2026. That reading was below both the long-term average of 25.62 meters per second and the previous low shown for that date, 13.68 meters per second. Forecasts suggested a brief reversal between November 9 and 11, followed by a return to westerly winds on November 12, but observations had not confirmed a reversal when the information was prepared on November 5.
If the winds do reverse and meet NOAA’s criteria at 60 degrees north and 10 hectopascals, the event could count as an unusually early major stratospheric warming compared with the November events listed in the guide through 2023. But the scientific label is not a direct forecast of cold or snow. Any influence on everyday weather may take about two to six weeks to move down through the atmosphere, and other factors, including El Niño, may shape the outcome. The vortex is undergoing a notable disruption; what kind of weather, if any, follows remains an open question that will require more observation.