An intensifying El Nino pushed sea surface temperatures in a key Pacific zone to a record peak in September, and the director of the European Union’s climate monitor said on Monday that the phenomenon could help make 2026 the hottest year ever recorded worldwide.
Forecasters had cautioned for months that this El Nino could become the strongest ever observed, and the latest temperature high arrived well before the event is expected to peak later this year.
Record Pacific sea temperatures and a contested ranking
Copernicus Climate Change Service said temperatures in the Nino3.4 monitoring area, a closely watched stretch of the Pacific, reached 29.70C last month, which it described as an all-time high. That figure surpassed the peaks recorded during earlier strong episodes in 1982/1983, 1997/1998 and 2015/2016.
Carlo Buontempo, the agency’s director, said the current event emerged in June and is “very exceptional”, but he cautioned that it is too early to determine whether it ranks as the strongest ever observed. Climate change is warming the oceans, which can make recent El Nino episodes look more intense than older ones and complicates comparisons across decades.
Copernicus said it had adopted a newer index that factors in the warming of tropical oceans. Under that measure, the present event has not yet overtaken past episodes. Buontempo said it remains a very large event even on that scale, and that it is unfolding in a considerably warmer climate. Forecasters also do not all use the same yardstick, and Japan’s weather agency said on Friday that conditions had reached their strongest level on record.
Global temperatures climb as the El Nino builds
Global average sea surface temperatures reached a record 21.05C for September, according to Copernicus, eclipsing the 20.92C high set in the same month of 2023. Surface air temperatures averaged 16.27C during September, making it the second-hottest September observed, following a record-breaking August.
The month ran 1.63C above the pre-industrial average, defined as the period from 1850 to 1900, and marked the second consecutive month in which warming exceeded 1.5C. Buontempo said temperatures would probably stay about 1.5C above normal into early next year.
What the El Nino means for 2026 and 2027
El Nino temporarily warms tropical Pacific waters and shifts weather patterns, raising the risk of drought and flooding while intensifying man-made warming. The phenomenon typically recurs every two to seven years and lasts roughly nine to 12 months, often pushing global temperatures higher in the year after its peak.
Experts have warned that this El Nino, combined with human-driven climate change, could make 2027 the hottest year on record as heat stored in the Pacific is released into the atmosphere. Buontempo, however, said 2026 could also set a record, and that repeating past patterns could mean record years in both 2026 and 2027. He noted that the last El Nino helped push 2024 to the top of the rankings after months of temperatures above 1.5C.
Buontempo stressed that while El Nino plays a role, the main driver of the rise is greenhouse gas emissions produced by human activity. Under the 2015 UN climate talks in Paris, nations pledged to hold warming significantly below 2C above pre-industrial levels while pursuing efforts to reach 1.5C. In September, the United Nations declared that the long-term 1.5C target would be missed within a matter of years.
Scientists say cutting fossil fuel emissions is essential to limit the period of overshoot above 1.5C and bring temperatures down as fast as possible.
