WMO forecasts record Pacific warming this October–December, with El Niño peaking in December; NOAA puts the chance of a “historic-strength” event at 83%. What the terms mean, past super El Niños, and why Tamil Nadu should prepare for both floods and a hot, dry 2027.
WMO forecasts record Pacific warming this October–December, with El Niño peaking in December; NOAA puts the chance of a “historic-strength” event at 83%. What the terms mean, past super El Niños, and why Tamil Nadu should prepare for both floods and a hot, dry 2027.
The El Niño now building in the Pacific Ocean could become one of the strongest ever measured. On October 8, 2026, the World Meteorological Organization (WMO) said sea-surface temperatures in the central and eastern tropical Pacific are forecast to reach record levels in October–December, with El Niño peaking around December. The same day, the US NOAA said a strong-to-very-strong event is likely to last into early 2027 (WMO, NOAA). Here is what the headlines mean — and what they don’t.
El Niño is the warm phase of the El Niño–Southern Oscillation (ENSO). Normally, trade winds push warm surface water west towards Indonesia and Australia. During El Niño these winds weaken and warm water spreads east across the equatorial Pacific, shifting where clouds form and rain falls around the world. It returns every two to seven years and usually lasts nine to twelve months (NOAA).
No. NOAA classifies El Niño as weak, moderate, strong or very strong. “Super El Niño” is an informal media term, usually used when the Niño-3.4 anomaly passes about +2°C. NOAA does track the odds of a “historic” event — a three-month relative index of +2.5°C or more — but “historic” describes rank, not a formal category.
| Indicator | Latest reading / forecast |
|---|---|
| Niño-3.4 anomaly | +2.1°C (NOAA, 8 Oct); September monthly value about +2.9°C |
| Eastern Pacific | Anomalies above +4°C in places; Niño-1+2 at +3.9°C |
| Oct–Dec forecast | About +3.7°C in Niño-3.4 — highest since records began (previous record +2.6°C, Nov 2015–Jan 2016) |
| Persistence | Near-100% chance El Niño lasts through Feb 2027 (13 centres); over 83% through Jan–Mar 2027 |
| “Historic” odds | 54% (Sep–Nov), 83% (Oct–Dec), 70% (Nov–Jan) |
| A first | Niño-3.4 sea temperature crossed 30°C on Oct 5 — first time in the observational record |
These are strong signals — but a forecast of record strength is not yet a record. The final ranking will be known only after the event peaks and observations are compared with past episodes.
| Event | What it is remembered for |
|---|---|
| 1876–78 | Linked to failed monsoons and the Great Famine in India — made far worse by colonial policy, poverty and poor relief |
| 1982–83 | Floods in the Americas, droughts elsewhere; drove modern ENSO science |
| 1997–98 | Indonesian fires and drought; extreme floods in Peru and Ecuador |
| 2015–16 | The previous record holder; drought in southern Africa and Southeast Asia, record global heat |
| 2023–24 | Among the strongest on record (WMO); pushed 2024 to record global warmth |
The WMO expects above-average temperatures across much of the globe, with wetter-than-normal conditions in places such as the Greater Horn of Africa, coastal East Asia and south-eastern South America, and drier conditions over the western Pacific and north-western South America. August 2026 was already the hottest August on record (WMO). Possible knock-on effects include heatwaves, higher electricity demand, crop stress, wildfires and coral bleaching.
Tamil Nadu gets most of its rain from the northeast monsoon (October–December), which behaves differently from the rest of India. In past El Niño years the northeast monsoon has often been heavy in Tamil Nadu — and this year’s season has started with up to 36 cm of rain in one night in North Chennai. The IMD expects normal rainfall overall this season, and normal to above normal in south and coastal Tamil Nadu.
The state’s El Niño Expert Advisory Committee has advised preparing for urban and riverine floods now and for a possibly hot, dry summer in 2027 — read our earlier explainer ›
El Niño is a real and measurable climate signal — but “super” and “historic” are descriptions, not verdicts, and a global forecast is not a district weather report. The right response is what Tamil Nadu is already doing: monitor closely, prepare early, and act on official warnings. For helplines and alerts, see the Monsoon Help Centre ›
El Niño Climate WMO NOAA Northeast Monsoon Tamil Nadu