El Niño, the natural Pacific Ocean weather pattern known for raising global temperatures, has officially begun, according to US scientists.
The US National Oceanic and Atmospheric Administration (NOAA) announced that El Niño conditions are now active in the tropical Pacific, following a sharp rise in sea surface temperatures over recent months.
Forecasters warn that the current development could evolve into a so-called “super” El Niño, potentially ranking among the strongest events ever recorded.
El Niño occurs when sea surface temperatures in the central and eastern Pacific Ocean rise significantly above average, altering global weather patterns. According to NOAA, temperatures have now crossed the 0.5°C-above-average threshold that defines the start of an El Niño event.
“El Niño conditions developed over the past month, as shown by above-average sea surface temperatures across the central to eastern equatorial Pacific Ocean,” the agency stated.
Scientists also observed changes in atmospheric winds above the equatorial Pacific, indicating that the atmosphere is beginning to respond to the warming ocean—a key sign that the event is strengthening.
What has surprised researchers is the strength indicated by early climate models. A strong El Niño is defined as sea surface temperatures more than 1.5°C above average, while very strong events exceed 2°C.
NOAA’s latest outlook suggests a 63% probability of a very strong El Niño occurring between November and January, potentially placing it among the most intense events recorded since 1950.
The three strongest El Niño events on record occurred in 1982/83, 1997/98, and 2015/16. Some forecasting models from the US and Europe even suggest temperatures in the tropical Pacific could rise above 3°C by the end of the year.
However, NOAA cautioned that the intensity of an El Niño does not always translate uniformly into global impacts.
“Even very strong El Niño events do not lead to the expected impact everywhere, but stronger events can more significantly tilt the odds in favour of expected outcomes,” the agency noted.
Experts warn that the phenomenon is unfolding on an already significantly warmer planet, increasing the risk of extreme global temperatures.
Professor Adam Scaife of the UK Met Office said the current event is occurring on top of long-term human-driven warming.
“This means that the actual temperatures in affected regions could well be unprecedented,” he said, adding that the combination of El Niño and climate change could push global temperatures to new records.
A strong El Niño typically raises global temperatures by around 0.2°C by releasing heat stored in the ocean into the atmosphere.
Despite a cooling La Niña phase earlier, 2025 still ranked among the hottest years on record, following 2024, the warmest year recorded globally.
Scientists warn that late 2026 and 2027 could see further temperature spikes, with a possibility that global warming thresholds may again be exceeded.
“In 2027, we’re likely to see excess heat on top of the global warming we’ve already got,” Scaife said, noting the increased risk of another year above 1.5°C of warming compared to pre-industrial levels.
The development has raised concerns about potential disruptions to global weather patterns, food production, and economic stability if the event intensifies as predicted.
