Sea-surface temperatures reflect strengthening El Niño – WMO, October 2026

The World Meteorological Organization (WMO) reports that El Niño is strengthening rapidly and is expected to peak in December 2026. The Niño 3.4 index rose from +1.6°C in June to +2.5°C in August and is forecast at around +3.7°C for October-December, the highest on record (the previous record was +2.6°C in 2015-2016). The chance of El Niño persisting through February 2027 is close to 100%. Above-normal temperatures are expected over large areas, with wetter-than-normal conditions in southeastern South America and drier-than-normal conditions in northwestern South America, southern Central America and parts of the Caribbean. WMO warns of risks of drought, flooding and extreme heat.