Polar Vortex Update: What NOAA Says the Early Disruption Means for U.S. Cold

As of 13:02 UTC (8:02 a.m. EST) on Saturday, Nov. 7, 2026, NOAA’s Climate Prediction Center (CPC) says “an unusually early sudden stratospheric warming (SSW) event is underway over the Arctic region”. CPC does not expect it to drive significant cold-air outbreaks into the U.S. for Nov. 21 to Dec. 4. In its Week 3-4 outlook issued at 3 p.m. EST on Friday, Nov. 6, it says El Niño is “favored to be the primary influencer” over that window, and that the expected pattern “limits the availability of Arctic air masses across North America that could drive any significant cold air outbreaks into the US” during it. The upper-level winds that define the polar vortex have slowed to about zero on CPC’s charts, but they had not clearly reversed when we checked. Below: what changed, what the terms mean, and why the headlines sound scarier than NOAA’s text.

What did NOAA say about the polar vortex this week?

CPC’s Week 3-4 discussion, issued at 3:00 p.m. EST on Friday, Nov. 6, is NOAA’s current statement on the polar vortex, and it calls the event an unusually early SSW that El Niño is expected to outweigh in late November and early December. Forecaster Adam Allgood wrote it, and it covers Saturday, Nov. 21, through Friday, Dec. 4, 2026. Here is the vortex part, in CPC’s words:

• The event: “an unusually early sudden stratospheric warming (SSW) event is underway over the Arctic region, with a weakening polar vortex potentially associated with a negative phase of the Arctic Oscillation (AO) and North Atlantic Oscillation (NAO) during the Week-1 period.”
• How long it lasts: “Dynamical model forecasts show this warming event to be relatively short-lived”. CPC adds that GEFS ensemble forecasts show the negative AO “weakening by the end of Week-2”.
• What wins out: “Despite these numerous conflicting signals, the ENSO response is favored to be the primary influencer of the Weeks 3-4 pattern during the outlook period.” ENSO is the El Niño-La Niña cycle.
• What it means for cold air: “Despite the SSW event, this pattern limits the availability of Arctic air masses across North America that could drive any significant cold air outbreaks into the US during the Weeks 3-4 period”.

The Arctic Oscillation is a measure of air pressure over the Arctic compared with the mid-latitudes. Its negative phase is often linked to colder air spilling south, which is why CPC mentions it. CPC ties that link to the coming week (Week 1). It does not tie it to late November.

We found no NOAA blog post on this event: the Climate.gov polar vortex blog, written by NOAA scientists, has been an archive since June 25, 2025, and its last post is from April 3, 2025.

What changed between CPC’s Oct. 30 and Nov. 6 wording?

CPC’s language moved from expecting a “major” SSW to saying an “unusually early” SSW is underway and is likely to be short-lived, with El Niño favored for late November and early December. Our El Niño November outlook page covers CPC’s Oct. 30 and Oct. 31 wording in detail. In short, CPC’s Oct. 30 Week 3-4 discussion said forecasts pointed to a transition into “a major sudden stratospheric warming (SSW) in a week”.

What the Nov. 6 discussion says:

• “Major” is gone. CPC now describes “an unusually early sudden stratospheric warming (SSW) event”. In SSW terms, “major” has a specific meaning, explained below.
• The warming is described as brief. CPC says models show it as “relatively short-lived”, with the negative AO weakening by the end of Week 2.
• CPC states a verdict for Nov. 21-Dec. 4. It weighs the SSW against El Niño and other signals, sides with El Niño for that window, and says the expected pattern limits Arctic air into the U.S.

Has the polar vortex actually reversed or collapsed?

Not clearly, as of CPC’s charts last updated at 11:56 UTC on Nov. 7: the analyzed wind at the reference level had fallen to about zero, but it had not clearly turned negative. CPC posts monitoring charts of the average west-to-east wind at 10 hPa (roughly 30 km, or about 19 miles, up) along 60°N latitude. They draw on two NOAA models, GFS and its ensemble, GEFS. Here is what the GFS and GEFS charts showed when we read them:

• The analysis: the wind peaked at about 23 m/s (around 50 mph) in late October, then fell steeply to about 0 m/s around Nov. 6-7, with a slight uptick at the latest analysis point. That low is below the bottom line on the chart, which marks the minimum in the climate record CPC plots for comparison.
• The forecasts: the GFS forecast lines dip slightly below zero, to about -5 m/s, and the GEFS lines dip to about -2 m/s. Both then climb back into positive territory over the following days.
• What that means: a brief, shallow reversal is possible in the model runs. It had not appeared in the analysis when we checked, and the quick recovery in the forecasts fits CPC’s “relatively short-lived” wording.

The UK Met Office said on Nov. 4 that “there remains uncertainty over whether a major SSW will occur”, and that any reversal looked “relatively weak and short-lived”. “Collapse” is a headline word, not a technical one. The vortex has weakened sharply. CPC’s text does not say it has collapsed, and the analysis line we read does not show a confirmed wind reversal.

What is the polar vortex, and is it the same as a cold snap?

No: the stratospheric polar vortex is a ring of strong west-to-east winds far above the Arctic, while a cold snap is weather at ground level. The UK Met Office places the vortex in the stratosphere, around 10 to 50 km (about 6 to 31 miles) above the surface. It circles a pool of very cold air over the North Pole and forms each autumn as the Arctic loses sunlight.

A U.S. cold outbreak happens much lower, in the troposphere, where day-to-day weather plays out. The two can be linked. When the vortex is badly disturbed, the jet stream lower down can become wavier. That can let cold air spill south somewhere in the Northern Hemisphere, sometimes weeks later. But the vortex itself does not “come” to the U.S. Many cold snaps have nothing to do with it, and a disturbed vortex does not guarantee cold in any particular place.

What is a sudden stratospheric warming, and how is a major one defined?

A sudden stratospheric warming is a rapid rise in temperature high over the Arctic that weakens the polar vortex’s winds; a “major” SSW is usually defined as the winds at 10 hPa and 60°N reversing from westerly to easterly. The Met Office explains how it happens. Large atmospheric waves in the lower atmosphere can travel upward and disturb the vortex, stretching it, pushing it off the pole or splitting it. In a major SSW, it says, “the westerly winds around the polar vortex can reverse and become easterly.”

That reversal test is why the 10 hPa, 60°N wind is the number everyone watches. A warming that slows the winds sharply without reversing them is often called a minor warming or a vortex disruption. CPC’s Nov. 6 text uses “SSW” without the word “major”.

Is the vortex splitting or being displaced?

The Met Office describes the vortex as unusually stretched, with forecasts suggesting it will be pushed increasingly off the North Pole; no source we read says a split has happened. There are two broad shapes a disturbed vortex can take:

• Displacement: the vortex stays in one piece but is shoved away from the pole, usually toward one side of the hemisphere.
• Split: the vortex is pulled into two smaller swirls. This is linked to “wave two” activity, where two large waves push in from opposite sides.

In its Nov. 4 deep dive, the Met Office said the vortex is “already unusually stretched”. It linked that to stronger-than-average “wave two” activity, and said forecasts suggest it will become “increasingly displaced from the North Pole”. The University of Reading’s Nov. 6 expert-comment release used “split” in its headline. Neither source says, and we do not say, that the vortex has split.

How long until a vortex disruption shows up at the surface?

Usually weeks, not days, and sometimes never. The Met Office says effects can work down into the lower atmosphere “over the following two to six weeks”. CPC’s Oct. 31 monthly discussion said that, should a November SSW occur, “impacts can be seen for up to 2 months”, usually as a negative Arctic Oscillation.

That lag is why the late-November and early-December window matters. It is also why CPC’s Nov. 6 verdict for Nov. 21 to Dec. 4 is the key line: CPC looked at that window and still favored El Niño’s pattern over the SSW’s.

Is this the earliest polar vortex disruption on record?

Some scientists say so, but NOAA has not: CPC calls the event “unusually early”, and the “earliest” claim comes from European forecasters quoted by AFP. AFP reported on Nov. 6 that Tim Stockdale and Frederic Vitart, principal scientists at the European Centre for Medium-Range Weather Forecasts (ECMWF), said: “As far as we know, this is the earliest stratospheric vortex disruption that has been observed.”

Sources give different earlier benchmarks:

• AFP says a November SSW had occurred only three times in records going back to the 1950s, in 1958, 1968 and 2025, “all on November 28.”
• Yahoo News (Nov. 6), in a passage that refers to experts speaking to Scientific American, says the earliest weakening previously recorded was Nov. 28, 1968.
• The University of Reading (Nov. 6) quoted Professor Andrew Charlton-Perez saying that in records back to 1979, with reasonable records to the 1940s, “we haven’t seen a sudden stratospheric warming earlier than very late November.”

FOX Weather’s Nov. 3 article put it conditionally: “If the reversal occurs, it would mark the earliest major polar vortex disruption on record.” Météo-France, quoted by AFP, called it “an unprecedented event”. On a possible El Niño link, the ECMWF scientists told AFP it “could have been a factor in making it more likely.” MIT’s Judah Cohen pointed more to a strong high-pressure system over Scandinavia and northwestern Russia. Cohen said climate change could be playing a role but stressed that this was speculation, and AFP noted that research has not confirmed such a link.

What does CPC’s outlook show for the U.S. through early December?

For Nov. 21 to Dec. 4, CPC leans warm for most of the northern U.S. and cold only for the Four Corners and much of Texas; its shorter-range outlooks lean warm for the West and center, with the East near to below normal in the 6-10 day period and near normal along the East Coast in the 8-14 day period. CPC’s outlooks give the probability that temperatures land in the warmest, middle or coldest third of the 1991-2020 normal. The table lists each outlook, the period it covers and when it was issued.

What each says about temperature:

• 6-10 day (Nov. 12-16, Nov. 6 issue): above normal favored over the western and central U.S., with CPC putting the chance of above normal at 80-90% over the northern Plains and nearby parts of Nebraska and Minnesota. Near to below normal is indicated for the eastern third, with below normal favored near the Atlantic Seaboard. CPC notes that overnight lows near freezing in the Ohio and Tennessee Valleys are “not unusual for mid-November”.
• 8-14 day (Nov. 14-20, Nov. 6 issue): above normal favored across most of the U.S., with CPC’s highest probabilities (above 80%) in eastern North Dakota and nearby northern Minnesota. Near normal is favored along the East Coast. Neither of these two discussions mentions the stratosphere or the polar vortex.
• Week 3-4 (Nov. 21-Dec. 4): above normal favored for Alaska, the West Coast states and the northern tier, with the highest probabilities over the Great Lakes and the Northeast. Above normal is slightly favored in the Southeast, though CPC says models show “a potential for colder temperatures extending into the region during Week-4”. Below normal is favored for the Four Corners and much of Texas.

An 80% chance of above normal is CPC’s estimate that the period’s average temperature falls in the warm third. It does not say how warm, and it does not rule out cold days. For the season as a whole, see our 2026-2027 U.S. winter forecast explainer .

Why are some headlines warning of a cold blast?

A weakened polar vortex is often linked to cold-air outbreaks weeks later, but headlines are not forecasts, and CPC’s Nov. 6 text points the other way for late November. Recent examples in Google News results include:

• Newsweek (Nov. 4): “Polar Vortex Disruption Raises Prospect of Major US Cold Snap”
• Patch’s state-by-state series (from Nov. 5): “Polar Vortex About To Go ‘Haywire’”, the same word Scientific American used in its Nov. 4 headline
• Men’s Journal (Nov. 6): “A Massive Polar Vortex Could Form in the Next 24 Hours”

Set those beside CPC’s own sentence: “Despite the SSW event, this pattern limits the availability of Arctic air masses across North America that could drive any significant cold air outbreaks into the US during the Weeks 3-4 period”. More cautious headlines exist too. CT Insider’s Nov. 6 headline said a record-early reversal “is possible”, which matches where things stood. Social-media maps of single model runs are not official outlooks either.

Why are the effects on the U.S. so uncertain?

Because a disrupted vortex does not decide where cold air goes, and this event is early, possibly brief and competing with a strong El Niño. The sources point to several reasons:

• Not every SSW reaches the surface. Some disturbances stay in the stratosphere. Even when they do work downward, the cold may go to Europe or Asia rather than North America.
• There is less cold air to tap this early. The Met Office notes that early in the season there is generally less cold air across the Northern Hemisphere than later in winter.
• The models show it as short-lived. CPC says the warming looks “relatively short-lived”, and the forecast winds on its charts recover within days.
• El Niño pushes the other way. CPC says its blended pattern is “strongly consistent with a canonical El Niño response” and limits the Arctic air available to reach the U.S. in Weeks 3-4. FOX Weather (Nov. 3) said a stronger Pacific jet could keep sending milder air across the country, and that “a disrupted polar vortex does not guarantee widespread or prolonged cold across the U.S.”
• Experts disagree on the weight. Cohen told AFP the disruption “really increases the chance of cold air outbreaks” across the Northern Hemisphere, while noting El Niño could “moderate or modify” the impacts.

When will NOAA update its outlook next?

CPC updates its 6-10 and 8-14 day outlooks every day between 3 and 4 p.m. ET, its next Week 3-4 outlook is due Friday, Nov. 13, and its December outlook comes Thursday, Nov. 19, 2026. Things to watch:

• Daily, 3-4 p.m. ET: the 6-10 and 8-14 day outlooks. The Nov. 7 issue, due this afternoon, replaces the Nov. 6 figures quoted above.
• Friday, Nov. 13: the next Week 3-4 outlook. It will show whether CPC still expects El Niño to outweigh the SSW for late November and early December.
• Thursday, Nov. 19: the December monthly outlook and the December-February seasonal update.
• Any day: CPC’s stratosphere monitoring charts. They show whether the 10 hPa wind at 60°N actually turns negative and how quickly it recovers.

Sources

• NOAA CPC: Week 3-4 Outlook and prognostic discussion (issued Nov. 6, 2026)
• NOAA CPC: 6-10 and 8-14 day prognostic discussion
• NOAA CPC: Sudden Stratospheric Warming Monitoring
• NOAA CPC: GFS zonal wind at 10 hPa, 60N, 2026/2027 (chart)
• NOAA CPC: GEFS zonal wind at 10 hPa, 60N, 2026/2027 (chart)
• NOAA CPC: 30-day outlook discussion (issued Oct. 31, 2026)
• NOAA Climate.gov (archived): Polar Vortex blog
• Met Office: Deep dive, could changes high above the Arctic influence the UK’s weather? (Nov. 4, 2026)
• Met Office: What is the stratospheric polar vortex and how does it affect UK weather? (Nov. 5, 2026)
• University of Reading: Early polar vortex split may impact UK snow and drought (Nov. 6, 2026)
• France 24 / AFP: Polar vortex faltering weeks earlier than ever recorded (Nov. 6, 2026)
• FOX Weather: Polar vortex disruption could be earliest on record as El Niño keeps US warm (Nov. 3, 2026)
• Yahoo News: The polar vortex is weakening unusually early (Nov. 6, 2026)