How a warming Pacific Ocean could bring a colder winter to the Northern Hemisphere

A warming Pacific Ocean might sound like it should mean a milder winter, but forecasters say the opposite could be true this year. El Niño occurs naturally when the tropical central and eastern Pacific becomes warmer than usual, triggering changes in atmospheric circulation that ripple around the globe — and a developing Super El Niño is now raising the odds of a disrupted Polar Vortex this winter.

According to a long-range analysis by Severe Weather Europe, past records show a higher probability of Polar Vortex disruptions during El Niño winters, especially in December and January. The Polar Vortex, a massive area of cold, fast-spinning winds above the Arctic, normally keeps extremely cold air confined near the North Pole; when it weakens, that cold air can spill south into North America, Europe and parts of Asia.

The latest seasonal forecast data suggests the developing Super El Niño may create conditions favourable for a weakening Polar Vortex during January and February 2027, with stratospheric wind speeds projected to drop well below the long-term average during mid-winter — a key signal of vortex strength.

If the pattern develops as projected, it could raise the chances of colder-than-normal temperatures and more snowfall across parts of the northern United States, southern Canada and some regions of Europe during the second half of winter, though local weather systems will still determine where the coldest conditions actually occur.