El Niño reaches a level never seen this early in the year: find out why 2027 is already in the spotlight
El Niño has already reached an exceptional intensity, even though its usual peak has not yet arrived. And its effects could be felt most strongly in 2027.
As of 21st September 2026, the daily surface temperature anomaly in the Niño 3.4 region had reached 3.11°C, surpassing the previous record of 3.08°C, recorded on 18th November 2015, during the 2015–2016 El Niño event.
A record broken several months before the peak
The Niño 3.4 region is located in the central tropical Pacific. Its temperature anomaly measures the difference between the sea surface temperature and a reference average. This indicator makes it possible to track the intensity of El Niño, a natural phenomenon that alters atmospheric circulation and rainfall across many parts of the world and temporarily raises the global average temperature.
What is particularly striking here is the date of the record. The strongest El Niño events generally reach their peak in November or December. Yet, in early September, the anomaly had already exceeded 3°C, compared with around 1.9°C at the same time in 1997 and 2015.
Monthly data confirm this trend. In August 2026, the Niño 3.4 anomaly reached around 2.45°C, exceeding the peak of almost all previous events, with the exceptions of 2015–2016 (2.75°C) and 1877–1878 (around 2.7°C), a value reconstructed from much sparser marine data.
Exceptional intensity, but still some uncertainty
Scientists also use RONI, an index that takes greater account of the overall warming of tropical oceans. In mid-September, it reached around 2.5°C, a record for this time of year, but still 0.7°C below the daily record set in 1982, reached at the end of December.
Looking ahead, 14 seasonal models and 674 simulations project a monthly maximum of around 4.1°C. In 80% of simulations, the peak falls between 3.4°C and 4.6°C. All of them exceed the 2015–2016 monthly maximum, with a projected difference of around 1.3°C.
This projection should nevertheless be treated with caution: no seasonal forecasting system has yet been tested against an event of such magnitude. The models also slightly overestimated August temperatures, with observations around 0.3°C lower than forecast.
Previous events nevertheless provide a useful reference point: all strong El Niño events observed so far have continued to intensify after mid-September. The models converge on a maximum between November 2026 and January 2027.
Why is 2027 already in the spotlight?
The influence of El Niño on global average temperatures does not appear immediately. Pacific warming generally precedes its effect on global temperatures by several months.
If the peak does indeed occur between November and January, much of this influence should therefore be felt in 2027 rather than 2026. This comes as 2026 is already on course to be the warmest or second-warmest year on record, according to the latest analyses.
El Niño is a natural phenomenon, but it is now developing in a climate already warmed by human activities. The September record is therefore only a first step. The coming months will show whether this exceptional intensity is sustained through winter and what impact it leaves on global temperatures in 2027.
News reference
Zeke Hausfather. (2026). Analysis: ‘Super El Niño’ breaks ‘remarkable’ all-time record.