El Niño is a natural warming of the central and eastern tropical Pacific that releases ocean heat into the atmosphere, and the 2026 event has already pushed sea surface temperatures to record levels. The World Meteorological Organization (WMO) says it is forecast to peak in December 2026 and persist through February 2027, with scientists warning the heat could push 2027 close to historic highs.
Global average sea surface temperature reached 21.05°C in September 2026, the highest ever recorded for that month, according to the European Union's Copernicus Climate Change Service (C3S). The previous September record was set in 2023.
What El Niño actually is
El Niño is a recurring climate pattern in which surface waters of the central and eastern tropical Pacific Ocean warm above average, altering wind and rainfall patterns worldwide. It is one phase of the El Niño–Southern Oscillation (ENSO) cycle, which also includes a cooling phase called La Niña and a neutral state.
WMO Secretary-General Celeste Saulo said in October 2026 that El Niño was firmly established and strengthening rapidly, adding that WMO forecasts indicated a near-100% likelihood it would persist through February 2027 and could potentially become one of the strongest El Niño events since at least 1950, according to WMO.
How the 2026 event compares to past El Niños
Forecasters track El Niño's strength through the Niño 3.4 index, which measures sea surface temperature anomalies in a reference zone of the equatorial Pacific. According to WMO, the index rose from +1.6°C above normal in June 2026 to +2.5°C in August, and is forecast to average roughly +3.7°C for October–December 2026, peaking in December.
That projected figure would exceed the previous record of +2.6°C set between November 2015 and January 2016, making the current event potentially the strongest since at least 1950, per WMO. Copernicus separately reported that the Niño 3.4 region hit an all-time high of 29.70°C in September, surpassing peak readings from the strong El Niño years of 1982–83, 1997–98 and 2015–16.
Niño 3.4 index: how 2026 compares
Period
Niño 3.4 anomaly
June 2026
+1.6°C
August 2026
+2.5°C
Oct–Dec 2026 (forecast, peak)
+3.7°C
Nov 2015–Jan 2016 (previous record)
+2.6°C
Why September 2026 broke global heat records
Copernicus reported that global surface air temperature in September 2026 averaged 16.27°C, making it the second-warmest September on record, 0.11°C cooler than September 2023 but still 1.63°C above pre-industrial (1850–1900) levels. The agency said this was a continuation of a run of months in 2026 in which global temperatures stayed above the 1.5°C threshold referenced in the Paris Agreement.
We are in a new run of months above 1.5°C, and with a strong El Niño still intensifying it is likely to last into 2027.
— Carlo Buontempo, Director, Copernicus Climate Change Service
Timeline: when El Niño peaks and ends
WMO's seasonal outlook, built from data shared by 13 national and international forecasting centres, puts the probability of El Niño persisting through February 2027 at near-100%. The agency expects the event to peak around December 2026 before gradually weakening.
Because El Niño releases stored ocean heat into the atmosphere with a lag, its warming effect on global air temperatures typically continues after the oceanic peak. That is why Buontempo and WMO both pointed to 2027 as a year likely to see elevated temperatures persist, even as the El Niño itself begins to fade.
What this means going forward
Scientists quoted by Copernicus and WMO describe the record warmth in 2026 as the combined result of a strong El Niño layered on top of long-term, human-driven climate warming. Neither agency has declared the event the strongest ever recorded by every measure, but both describe it as among the most intense since systematic records began around 1950.
Questions
What is El Niño in simple terms?
El Niño is a periodic warming of sea surface temperatures in the central and eastern tropical Pacific Ocean that shifts weather patterns worldwide; it is part of the ENSO cycle, which also includes the cooling La Niña phase, according to WMO.
When will the 2026 El Niño peak?
WMO forecasts the event will peak around December 2026, with a near-100% probability of persisting through February 2027.
Is the 2026 El Niño the strongest ever recorded?
It is among the strongest since at least 1950, per WMO, and Niño 3.4 sea surface temperatures exceeded past strong events in September per Copernicus — but neither agency has confirmed it is the strongest on every metric.
Why did global sea temperatures hit a record in September 2026?
Copernicus reported global average sea surface temperature of 21.05°C in September 2026, the highest for that month on record, occurring alongside a strengthening El Niño that is releasing heat stored in the Pacific.
Could 2027 be the hottest year on record?
Copernicus director Carlo Buontempo said temperatures exceeding the Paris Agreement's 1.5°C threshold are likely to continue into 2027 given the intensifying El Niño, though neither agency has formally forecast 2027 as a record year in the sources reviewed.
How the world is telling it
TurkishTurkish outlets NTV and Euronews Türkçe frame the story around the record 21.05°C global sea temperature and the Niño 3.4 reading of 29.70°C reported by Copernicus, and detail the WMO timeline showing El Niño peaking in December 2026 and persisting through February 2027, with warnings that effects could extend into 2027.
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