The Met Office has issued a fresh warning that the UK faces "unprecedented" wet and stormy weather this autumn and winter, driven by an exceptionally intense El Niño developing in the Pacific Ocean.

Forecasters say north-western Europe, including Britain, is now likely to see far wetter and stormier conditions than normal in the coming months, following a summer of extreme heatwaves across Europe.

"We should be clear that this is an unprecedented event. We have never seen an El Niño signal this intense in our forecasts," said Professor Adam Scaife, head of long-range forecasting at the Met Office. He explained that while a typical El Niño brings equatorial Pacific sea-surface temperature rises of between 1C and 2C, warming in the coming months is forecast to exceed 3C, which would make it the largest event since the 19th century.

According to Met Office science fellow Dr Nick Dunstone, the immense release of ocean heat into the atmosphere means 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 pre-industrial period."

El Niño is a naturally occurring climate phenomenon that emerges every two to seven years and usually lasts for about a year, occurring when sea temperatures in the tropical eastern Pacific rise at least 0.5C above average. Current readings are already more than 2C above normal, with deeper waters running up to 8C above average.

Some long-range models project sea surface anomalies could reach 4C above average. Dr Zeke Hausfather, a climate scientist at US research group Berkeley Earth, noted that "it's not beyond the realm of possibility to say this might be the strongest El Niño event in 500 or even 1,000 years."

Worldwide effects are already materialising. Alongside the storm risk for the UK and north-western Europe, the Met Office warns of heightened drought risks across the tropics, southern Africa and north-east Australia. In 2026, South Asian monsoon rainfall has fallen well below normal, Atlantic hurricane numbers remain suppressed with only three named storms so far, the Panama Canal has reduced vessel transits, and flood risks have surged in Ecuador, Peru and the southern US.

Professor Stephen Belcher, the Met Office's chief of science and technology, noted that while recent European heatwaves reflect the ongoing effects of human-induced climate change, this large El Niño highlights how natural variations in the climate system can add to the underlying warming trend.

A 2021 Intergovernmental Panel on Climate Change (IPCC) assessment found El Niño intensity has increased since 1950, though long-term historical variability makes a direct causal link difficult to confirm. What is certain is that this record-setting system is unfolding on top of an already warmer climate.

I will continue tracking the Pacific data and long-range forecasts as autumn approaches — check back for further updates.