The Met Office is warning that 2026 is going to be renowned for 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.”

Analysis of historical data and computer simulations highlight the anomalous global rainfall patterns from El Niño. These are also well documented in a variety of impacts and humanitarian studies which detail the more sector-specific impacts.

The Indian summer monsoon is one of the regional weather patterns affected as El Niño grows and it is already running well below normal rainfall. Other regions at risk of low rainfall include Central America, west Pacific nations and tropical South America. El Niño also affects tropical cyclones and suppresses Atlantic hurricanes by increasing wind shear in the tropical Atlantic. Consistent with this, there have only been three storms so far this season, but it only takes one large hurricane to lead to devastating impacts.

What could an unprecedented El Niño mean for the UK?

The Met Office said 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, the Met Office expects 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. Dr Nick Dunstone, who leads the Climate Dynamics group since 2014 - part of the Monthly to Decadal Climate Prediction area led by Prof. Adam Scaife. explained:

“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, the Met Office’s Chief of Science and Technology commented:

“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.”

The Met Office is monitoring and continually running new forecasts as well as working with government departments to understand the wider implications of the 2026 El Niño and will provide further updates later in the year.