For a few weeks now, forecasters have said that a cold-air pattern known as the polar vortex is starting its season stronger than usual.
The polar vortex is a stream of wind that forms high above the North and South Poles at different times of the year, though this specific one sits above the North Pole and rages through winter.
While this sounds like a recipe for chilling, blustery weather, a strong polar vortex helps to contain very cold winds and conditions within the North Pole. This actually protects the UK from freezing weather.
But while experts thought that the current polar vortex seemed like it might become weaker in January of 2027, some predictions have since put this much sooner – as early as the beginning of November.
CNN points out that disruptions like these are almost “unheard of” this soon into winter.
They added that if the predicted event actually happens, it “could also be one of the earliest significant polar vortex disruptions recorded since the dawn of the satellite era”.
What could a weaker polar vortex actually mean for the UK?
There are lots of ways in which the polar vortex can grow weaker and spread south. But perhaps the most significant to us are sudden stratospheric warmings (SSW), which the Met Office says can make the winds in the vortex reverse direction.
This can sometimes make the jet stream “snake” more, which means that “northern Europe, including the UK, is likely to get a long spell of dry, cold weather”, per the Met Office.
SSWs have therefore previously been linked to “extreme cold, winter snow events”.
As of the time of writing, some of the European Centre for Medium-Range Weather Forecasts (ECMWF)’s forecasts predict an SSW as soon as 6 November.
But there’s a catch or two. Not only do neither a weakened polar vortex nor an SSW not necessarily mean we’ll face a frozen winter here in the UK, but polar vortex expert Judah Cohen from MIT has put the odds of this reversal at about 25%.
However Cohen did tell USA Today that he expects the polar vortex to “stretch” this week, adding that when these “stretched” conditions meet weather patterns in areas like East Asia, they might turn into something like a full-blown SSW.
“Though I don’t rule out that it will just resolve itself into another stretched polar vortex in the end,” he continued.
We were already at greater risk of a cold, wet winter in the UK
The polar vortex isn’t the only factor that might affect the UK’s weather this winter.
El Niño could also make our winter colder, wetter, and stormier, and “is associated with increased risk of cold snaps,” the Met Office shared.
Prof Ilan Kelman, Professor of Disasters and Health at University College London, told HuffPost UK: “El Niño is expected to make the UK’s autumn milder, wetter, and stormier, the UK’s winter colder and stormier, and next year’s UK summer hotter.
“We should be ready to deal with such weather, although we are not. The expected hotter summer is particularly challenging given climate change’s evident worsening of heatwaves, in the UK and around the world”.
