Disruption in the polar vortex is anticipated in early years in January after stratospheric warming 

According to ECMWF and NOAA extended-range projections, a Sudden Stratospheric Warming (SSW) event in the course of the Arctic during the period of mid-January 2026 is predicted to weaken and replace the Polar Vortex. It is likely to continue the disturbance downwards in the next several weeks, increasing the risk of Arctic air breakouts and lower-than-average air temperatures in some parts of North America and Europe in the second half of January 2026.

It is believed that forecast models have indicated that there could be a Sudden Stratospheric Warming (SSW) event over the Arctic in mid-January 2026. The variations in the temperature between the 10 and 30 hpa reveal that the polar stratosphere is rapidly increasing, pointing towards a distortion of the normal circumpolar circulation that traps cold air around the high latitudes in winter.

The European Centre of Medium-range Weather Forecasts (ECMWF) and the Global Forecast System (GFS) predict that there will be a further warming process in mid-January, resulting in an extended and displaced Polar Vortex. 

Although the model guidance is yet to show the total reversal of the Stratospheric winds at 10 hpa, the disturbance is so intense as to produce changes in the hemisphere pattern of waves and influence the surface weather later this month.

It takes 1 to 3 weeks to propagate down the troposphere. Experience of current ensemble data indicates that this process may result in superior atmospheric blocking around Greenland and the North Atlantic, preferring northerly and north-easterly breeze in Europe.

The resultant cold anomalies would most probably be over Scandinavia, the British Isles and even some of Central and Eastern Europe in the second half of January.

The emerging Stratospheric irregularity is predicted to favour additional troughing of the western and central regions of North America, which enables the Arctic air to periodically push north to the Plains and the Great Lakes and northeastern parts of the US. The trend is likely to be dynamic, and it will have periods of mild and cold weather and not a complete freeze over the continent.

As much as the weakening of high-altitude circulation is observed, there are regional surface actions that are influenced by the degree of stratosphere-to-troposphere connection, and simultaneous mobile events like the North Atlantic Oscillation (NAO) and the Arctic Oscillation (AO). Model groups shift to the negative AO phase after the middle of January.

Though the confidence of the forecasts is still moderate until the beginning of January, the stratospheric temperature abnormalities are expected to intensify, and the Polar Vortex is still not in place at the pole. If downward coupling proceeds, enhanced snow activity, colder air masses and increased jet stream waviness are anticipated to emerge slowly from mid to late January 2026 across the Northern Hemisphere.