Why this score UN agency for meteorology; annual State of the Global Climate reports synthesize the major observational records.
Our latest Global Seasonal Climate Update forecasts that sea surface temperatures in the tropical Pacific – the epicentre of El Niño - may rise to 3.8°C above average during November 2026 to January 2027.
Not yet checkable: it settles on the November 2026–January 2027 Niño 3.4 average, early in 2027. 'May rise to 3.8°C' is scored as reaching 3.5°C or more; the seasonal record is +2.6°C (2015–16). WMO named neither the index nor its baseline.
For October-November-December, the seasonal average Niño 3.4 sea surface temperature anomaly is forecast to reach approximately +3.7°C, peaking around December.
Not yet checkable: it settles on the October–December 2026 Niño 3.4 average, early in 2027. The previous seasonal record was +2.6°C (2015–16). WMO did not state the anomaly's baseline.
El Niño will strengthen to a very strong event peaking towards the end of 2026, and forecasts put at nearly 100 percent the likelihood it persists through February 2027.
Not yet checkable. It settles once the peak three-month Oceanic Niño Index is known and whether El Niño ran unbroken through February 2027; 'very strong' conventionally means an ONI of 2.0°C or higher. WMO calls this its most confident El Niño outlook ever.