The developing El Niño in the Pacific Ocean has exceeded previous records, with sea-surface temperatures in the central equatorial Pacific now higher than during any previous event in the observational record, according to the Met Office.
Scientists have been monitoring the event for several months, with forecasts indicating that 2026 could see an unprecedented El Niño. The event is expected to build toward its seasonal peak later this year.
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. 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.”
Scientists use several measures to assess the strength of El Niño, including the Oceanic Niño Index (ONI), which measures sea-surface temperature anomalies in the Niño 3.4 region of the tropical Pacific.
Alternative measures such as the Relative Oceanic Niño Index (RONI) are also being used. RONI compares temperatures in the Niño 3.4 region with those across the rest of the tropical oceans, providing additional information in a warming climate.
The Met Office said scientists are also examining atmospheric pressure patterns, trade wind strength and subsurface ocean temperatures to assess the event and its potential impacts.
El Niño can influence rainfall, temperature and storm tracks around the world. The Met Office said this year’s Indian summer monsoon has already been running below normal, consistent with the developing El Niño signal, while southern Africa could face increased drought risk as the event strengthens.
El Niño is associated with an increased likelihood of wetter and stormier conditions across northwestern Europe during autumn and early winter, followed later in the season by an increased risk of cold snaps.
Strong El Niño events can also contribute to higher global average temperatures by releasing additional heat from the ocean into the atmosphere.
Met Office science fellow Dr Nick Dunstone said, “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.”
He added that 2027 is “very likely” to replace 2024 as the warmest year on record.
Related news, August 2026 was joint warmest month on record, Copernicus reports