Met Office warns El Niño could weaken polar vortex, extending UK cold spell
The Met Office says a strong El Niño developing later this year may weaken the stratospheric polar vortex, raising the chance of prolonged cold snaps across Britain.
The Met Office has issued a fresh outlook indicating that a major El Niño, projected to become one of the strongest on record, could disrupt the stratospheric polar vortex later this winter. According to research cited from NOAA's Chemical Sciences Laboratory, such a breakdown often leads to sudden stratospheric warming, a process that can force frigid air to descend and alter the jet stream. This may result in a persistent blocking pattern, extending cold weather well beyond the typical winter months.
In addition to the chill, the agency warns of heightened chances for wet, stormy weather and associated flooding. Chief forecaster Will Lang described the development as a "subtle shift in the odds" rather than a guaranteed outcome, while Professor Adam Scaife highlighted the unprecedented scale of one outlet El Niño. The UK, which just experienced its hottest summer on record, now faces the prospect of unsettled, colder conditions in the coming months.
Why it matters
A weakened polar vortex could bring extended cold, wet weather and flood risk to the UK this winter.
How this story developed
- Aug 31 UN warns that a record-breaking El Niño could trigger worldwide extreme weather
- Sep 3 UN says the El Niño is expected to remain in place until February 2027.
- Sep 5 Czech forecasts include a possible rapid temperature rise to around 30 °C early next week.
- Sep 7 Britain announced cuts of more than 80 % to bilateral aid in eight African states.
- Sep 7 UK models show a higher likelihood of stormier, wetter conditions during autumn and winter.
- Sep 9 A brief spell of 27‑28 °C heat is expected in southeast England on Sunday.
- Sep 9 The contiguous United States experienced its warmest June-August period on record, with an average temperature of 74.4°F, according to NOAA.
- Sep 10 August 2026 set a new all‑time monthly heat record and drought drove the two biggest western water reservoirs to their lowest historic levels.
- Sep 13 Forecasts now show showers spreading across the west and east of the UK by Tuesday, following the brief heat spike.
- Sep 20 New forecasts show London reaching about 24 °C by Monday and showers expected in Manchester from Thursday.
- Sep 21 The system, now classified as a hurricane, is positioned about 270 miles south-southeast of Manzanillo and 190 miles south-southwest of Zihuatanejo, with sustained winds of 80 mph. Forecasts suggest it could reach major-hurricane strength by Tuesday and maintain a trajectory offshore while dumping 4-8 inches of rain across Guerrero and Michoacan through Thursday. Tourist hubs such as Acapulco, Puerto Vallarta and Guadalajara may experience rough seas and gusty conditions, and the moisture could trigger flash-flood threats in the U.S. Southwest later in the week.
- Sep 23 Polo intensified to Category 5 with maximum sustained winds of 175 mph.
- Sep 24 Authorities opened shelters and deployed thousands of military and Red Cross personnel to assist affected communities.
- Sep 29 Probability estimates now place a greater than 90% chance that the El Niño will remain very strong through February 2027.
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