WMO forecasts record El Niño sea-surface temperatures by December
WMO forecasts record sea-surface temperatures in the central-eastern tropical Pacific for October-December 2026, with El Niño likely to persist through February 2027.
The story in focus
The World Meteorological Organization forecasts record sea-surface temperatures in the central and eastern tropical Pacific for October-December 2026 as El Niño strengthens, likely bringing above-average global temperatures and shifting rainfall patterns.
- Niño 3.4 index rose from +1.6°C above normal in June 2026 to +2.5°C in August.
- Forecast seasonal average for October-December is about +3.7°C, the highest since observations began.
- WMO cites a near-100% likelihood that El Niño persists through February 2027.
El Niño strengthens toward record peak
The World Meteorological Organization's monthly Global Seasonal Climate Update forecasts sea-surface temperatures in the central and eastern tropical Pacific to rise to record levels during October-November-December 2026. The Niño 3.4 index, a key measure, increased from an average +1.6°C above normal in June to +2.5°C in August. The seasonal average is forecast to reach approximately +3.7°C, peaking around December—the highest since observations began and above the previous record of +2.6°C in November 2015-January 2016.
WMO Secretary-General Celeste Saulo said El Niño is firmly established and strengthening rapidly, with forecasts indicating a near-100% likelihood it persists through February 2027. She noted the event could be one of the strongest since at least 1950. The probability reflects consensus across thirteen national and international centres using ocean buoy, satellite and radiosonde data.
Global weather and ocean patterns
According to WMO, El Niño is likely to bring above-average temperatures to much of the globe and shift rainfall patterns, increasing drought and flood risks in different regions. A positive Indian Ocean Dipole is expected to peak in October and decline, with an October-December seasonal anomaly forecast at about +0.5°C. Equatorial Atlantic sea-surface temperatures are forecast to remain above normal.
Saulo explained that El Niño releases heat the ocean has already stored rather than adding new heat, which is why strong events often coincide with record-hot years. She said the ocean is the warmest ever measured, meaning more heat is available to release.
How high is the Niño 3.4 index forecast to reach?
The seasonal average Niño 3.4 sea-surface temperature anomaly is forecast to reach approximately +3.7°C for October-November-December 2026, peaking around December—the highest since observations began.
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