Developing El Niño becomes strongest on record weeks before expected peak

Developing El Niño becomes strongest on record weeks before expected peak By Ben Rich, Lead Weather Presenter, and Simon King, Lead Weather Presenter The ongoing El Niño climate anomaly is now the strongest ever recorded, according to scientists tracking Pacific Ocean temperatures. Daily sea‑surface temperatures in a key region of the central‑eastern Pacific reached 3.05 °C above the long‑term mean on 19 September, surpassing the previous high of 3.02 °C set during the powerful El Niño of 2015. While some longer‑term indicators have not yet hit record levels, experts say the peak is still to come later this year. El Niño can trigger major shifts in global weather patterns, and the Met Office notes that many of the anticipated effects are already being felt. **What is El Niño and how is it measured?** El Niño is a naturally occurring cycle that recurs roughly every two to seven years and typically lasts about a year. Normally, trade winds blow from east to west across the Pacific; during an El Niño these winds weaken or reverse, allowing warm water to drift eastward. The release of heat from the ocean into the atmosphere can raise global temperatures and alter weather patterns worldwide. Forecasters declare an El Niño when temperatures in a designated Pacific zone stay at least 0.5 °C above normal for an extended period. Different metrics gauge the phenomenon’s strength. The Oceanic Niño Index (ONI) compares monthly sea‑surface temperatures in the central‑eastern Pacific with the historical average; it is this index that has just been broken. Many scientists, including forecasters in the United States and Australia, also use the Relative Oceanic Niño Index (RONI), which measures the warmth of the El Niño region relative to the rest of the tropical oceans, thereby accounting for background climate‑change warming. On the RONI scale the current event is not yet a record‑breaker, though further announcements are expected in the coming weeks. Professor Adam Scaife, Head of Long Range Prediction at the Met Office, said: “We have been signalling for months that the developing El Niño will be an unprecedented event.” He added: “The fact that it has already exceeded previous records – with several weeks to go before it peaks later this year – shows the enormity of this El Niño.” **Impacts of El Niño already being felt globally** Each El Niño unfolds differently, so its influence on global weather is not guaranteed. The unprecedented strength of this episode does not automatically translate into unprecedented weather impacts. Professor Scaife noted: “Scientists are still assessing whether the impacts will be in proportion to its magnitude, but we are already seeing expected effects worldwide.” El Niño raises the odds of storms and floods in some areas while increasing the risk of drought and wildfires in others. In India, El Niño years usually bring below‑average monsoon rainfall. Data from the India Meteorological Department show that, up to 22 September, the southwest monsoon delivered 15 % less rain than normal. A typical El Niño signature is reduced Atlantic hurricane activity due to altered high‑level wind patterns. So far in 2026 no Atlantic hurricanes have formed, establishing a new record for the latest day without a hurricane since systematic storm monitoring began. Other anticipated effects—some already evident—include heightened flood risk in coastal parts of Ecuador, Peru and the southern United States, and an elevated threat of drought and wildfires in Brazil, Australia and Indonesia. Such weather shifts can reverberate through crop yields, food security and economies around the globe. **Will there be an impact on UK weather?** The UK lies thousands of miles from the tropical Pacific, so El Niño’s signal there is often less distinct than in other regions. Nevertheless, the phenomenon can increase the likelihood of wet and stormy conditions across north‑west Europe during late autumn and early winter. A Met Office forecast issued this autumn highlighted “signals for increased rainfall and storminess in autumn present in the UK,” especially through November and December. The winter of 2015‑2016, which coincided with a very strong El Niño, produced a series of large storms that experts at the time described as the most extreme flooding on record. El Niño can also be linked to cold snaps in the UK’s late winter, although the relationship is not strong and historical records are mixed. The so‑called Big Freeze of winter 2009/2010, the coldest in three decades at the time, occurred during an El Niño, while the El Niño winter of 2006/2007 was unusually warm. As this unprecedented El Niño approaches its probable peak toward the end of 2026, scientists will continue to monitor its evolution and its worldwide weather repercussions.