Britain is bracing for an "unprecedented" El Niño event that forecasters predict will bring severe storms and heavy rain throughout the upcoming autumn and winter seasons. This natural climate phenomenon, driven by a significant rise in sea temperatures in the tropical eastern Pacific, is expected to be the most impactful weather event since the 19th century.
El Niño develops when sea surface temperatures in the tropical eastern Pacific rise 0.5 degrees Celsius above the long-term average. Current calculations from the Met Office suggest these temperatures could exceed 3 degrees Celsius, with some climate groups projecting an even stronger event, potentially 4 degrees Celsius above average. This intensity has led experts to suggest it could be the strongest El Niño in 500 to 1,000 years, though such historical comparisons are difficult to substantiate.
"We should be clear that this is an unprecedented event. I 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 added that a typical El Niño causes a 1 to 2 degrees Celsius rise in equatorial Pacific sea-surface temperatures, with 2 degrees Celsius considered a significant event. The current projections suggest 2026 will far exceed recent experiences of El Niño and its global climate influences.
While El Niño events typically heighten the risk of drought in tropical regions, southern Africa, and northeastern Australia, they are projected to bring wetter and stormier conditions to northwestern Europe, including the UK.
Beyond regional weather impacts, El Niño events are known to drive an increase in global average temperatures. The Met Office forecasts that 2027 is "very likely" to become the hottest year on record, surpassing 2024 and temporarily exceeding 1.5 degrees Celsius above the pre-industrial period. This is because significant heat released from the ocean to the atmosphere during large El Niño events leads to a rise in global average temperatures, particularly in the year following the winter peak of the event.
Professor Stephen Belcher, the Met Office's chief of science and technology, noted that while recent heatwaves across Europe are a reminder of climate change's effects, the current El Niño highlights the role of natural variations in the climate system, which can exacerbate climate change stresses.
The UK has already experienced extreme weather, with recent heatwaves leading to the driest July in 190 years and pushing much of England and all of Wales into drought. Reservoir levels have fallen significantly below average, impacting water systems, wildlife, farmers, and infrastructure. Despite recent showers, officials warn that it could take months of sustained rainfall to replenish water sources and officially end drought conditions.
The National Drought Group, comprising meteorological, regulatory, governmental, water, farming, scientific, and conservation bodies, has moved to weekly meetings to enhance its response to extreme weather. They caution that current forecasts do not indicate sufficient rainfall this autumn to recover from drought before the end of the year.
Recent extreme temperatures have also marked 2026 as a record-breaking year. The UK recorded its hottest day of the year at 38.1 degrees Celsius on August 13. Furthermore, 2026 has become the first year on record with three separate days reaching the 37 degrees Celsius threshold. These heatwaves have also contributed to a record high number of wildfires across England and Wales so far this year.