Britain's weather could be set for a dramatic change after months of scorching temperatures, with forecasters warning of a wetter and stormier autumn. The Met Office has said a powerful El Niño developing over the Pacific Ocean could become the strongest seen for more than a century.
While the phenomenon is expected to push global temperatures even higher in 2027, its impact on the UK could bring increased rainfall and storms later this year.
Met Office warns of 'unprecedented' event
Prof Adam Scaife, the Met Office's head of long-range forecasting, said: "We should be clear that this is an unprecedented event. I have never seen an El Niño signal this intense in our forecasts."
Pacific sea temperatures are expected to rise by around 3C during the event. A typical El Niño sees temperatures increase by more than 1C, while a rise of 2C is already considered particularly significant.
Speaking to BBC Radio 4's Today programme, Prof Scaife said: "We're expecting the biggest El Niño for over a century, peaking at something over 3C. That is unheard of in modern climate records … It's up 2C degrees already."
Autumn rainfall and storminess signals
He added that the effects could begin to influence Britain's weather during the autumn. Prof Scaife said: "Then there are wave-like disturbances that come out from the tropics and affect places like the UK. So we already see signals for increased rainfall and storminess in the autumn here in the UK around November time."
The potential change comes after an exceptionally hot and dry summer. A string of heatwaves and prolonged lack of rain resulted in the UK's driest July in 190 years.
Drought conditions persist
Almost three-quarters of England and the whole of Wales have been pushed into drought conditions, putting pressure on reservoirs, farmers and water supplies.
Despite heavier showers hitting parts of the country recently, officials have warned that sustained rainfall could be needed for months before depleted rivers, groundwater and reservoirs fully recover. Seven reservoirs in England are currently classed as having "exceptionally low" storage levels, while overall reservoir storage stands at 63% – 16 percentage points below the long-term average for this point in the year.
Global impacts expected
The developing El Niño could also have major consequences beyond Britain. The Met Office expects its effects to be particularly severe across parts of the tropics, while southern Africa and north-east Australia face a heightened risk of drought.
The phenomenon could also contribute to another surge in global temperatures next year. Dr Nick Dunstone, a science fellow at the Met Office, said: "During large El Niño events, significantly more heat is released from the ocean to the atmosphere, leading to an increase in global average temperature, particularly in the calendar year following the winter peak of the El Niño. Hence, 2027 is very likely to replace 2024 as the warmest year on record and be another year to temporarily exceed plus 1.5C above the preindustrial period."
