A record set in September
The 2026 El Nino is already the strongest on record by one key measure, and it has not finished growing. On September 21, the daily sea-surface temperature anomaly in the central equatorial Pacific reached about 3.1C above the 1991-2020 average. That is above the previous record of 3.02C, set during the El Nino of November 2015.
The event emerged in June. Scientists at NOAA's Geophysical Fluid Dynamics Laboratory describe it as remarkable and expect it to peak within the next few months. Different datasets put the anomaly at slightly different levels because they use different baselines, but all of them show a record.
What the forecasts say
NOAA gives a greater than 90 per cent chance of a very strong El Nino during the autumn and winter of 2026-27. It also estimates a 75 per cent chance that the October-to-December average reaches 2.5C or more above normal. If that happens, the event would exceed every El Nino in NOAA's records, which go back to 1950.
Forecast models project a monthly peak of about 4C later this year. Most individual model runs fall between 3.4C and 4.6C. Those numbers would place this event well above the strong El Ninos of 1982-83, 1997-98 and 2015-16.
What it could bring
El Nino shifts where heat and rain end up. A strong event can bring drought to parts of Australia, Indonesia and southern Africa, heavy rain to Peru and Ecuador, and warmer winters across parts of North America. It also raises global average temperatures, because ocean heat is released into the atmosphere.
The 1997-98 event flooded large areas of Ecuador and cut off roads. This year's event is arriving on top of a long-term warming trend, so its effects may be more severe than earlier ones of similar strength. Scientists caution that no single storm can be blamed on El Nino, and that its influence varies by region and season. Monitoring groups will publish updated forecasts each month through the winter.