On 21 August the Met Office announced that according to its forecasts, and those of other organisations, 2026 is going to witness the development of the largest El Niño in living memory and what is probably the largest such event since the 19th century.

“We should be clear that this is an unprecedented event”, said Professor Adam Scaife, Head of Long Range Forecasting at the Met Office. He added: “I have never seen an El Niño signal this intense in our forecasts. A typical El Niño leads to an equatorial Pacific sea-surface temperature rise of between 1-2 degrees, with 2oC being a really big event. This implies that if the forecast is accurate – and other forecast systems show similar extreme values – then 2026 will far exceed our recent experience of El Niño and its worldwide climate influences.”

What could an unprecedented El Niño mean for the UK?

The El Niño is now growing towards its peak in winter, and the impacts will affect not only the tropics but also the mid latitudes and so southern Africa and north-east Australia are expected to be at heightened risk of drought. Closer to the UK, we expect the influence of El Niño to start to increase the chances of wetter, stormier conditions for NW Europe, including the UK, in the coming autumn and early winter.

El Niño events also drive an increase in global average temperature, as Dr Nick Dunstone explains: “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 +1.5 C above the preindustrial period”.

Professor Stephen Belcher is the Met Office’s Chief of Science and Technology. He said: “This summer we have experienced heat waves across Europe reminding us of the effects of climate change, this large El Niño is a reminder that natural variations in the climate system are also at play, adding to the stresses of climate change.”