El Niño forecast to become very strong by late 2026, raising extreme weather risks into 2027
El Niño is forecast to strengthen to very strong intensity during late 2026, with the World Meteorological Organization (WMO) indicating an exceptionally high likelihood of nearly 100% that El Niño conditions will persist through February 2027. NOAA’s Climate Prediction Center (CPC) separately gives a greater than 90% chance of a very strong event during Northern Hemisphere fall and winter 2026–27. A very strong El Niño increases the likelihood of major shifts in rainfall and temperature patterns across many regions, although the severity of impacts varies by location and season.
Image credit: NOAA
El Niño is firmly established in the central-eastern equatorial Pacific and is forecast to strengthen to very strong intensity before peaking toward the end of 2026, the World Meteorological Organization (WMO) said on September 3.
Forecasts from WMO Global Producing Centers indicate a nearly 100% probability that El Niño will persist through December 2026–February 2027, increasing the likelihood of major changes in rainfall and temperature patterns across many regions.
Sea surface temperatures across the central-eastern equatorial Pacific have risen sharply. WMO reported that the Niño 3.4 anomaly averaged approximately +1.5°C (+2.7°F) during May-July 2026 and reached +2°C (+3.6°F) in July.
Weekly Niño 3.4 anomalies increased to approximately +2.2°C to +2.6°C (+4°F to +4.7°F) between late July and mid-August, indicating continued intensification.
WMO also reported subsurface ocean temperatures more than 8°C (14.4°F) above average in some areas during July and early August. The combined surface, subsurface and atmospheric signals, together with agreement among seasonal prediction systems, support continued strengthening and persistence into early 2027.
“El Niño in Spanish means boy child – but it has the potential to deliver a massive blow to communities and economies across the world. We are already seeing disruption and devastation from droughts and floods, and we expect these impacts to increase as El Niño intensifies,” said WMO Secretary-General Celeste Saulo. “This exceptional El Niño demands exceptional preparation and response,” she said.
“El Niño is being supersized before our eyes. The science leaves no room for doubt: the planet is in uncharted waters, and those waters are heating up. Sea surface temperatures are rising, temperatures keep climbing, and the world is in the danger zone of extreme weather. The race now is between rising risks and our commitment to take climate action and protect people. We must win that race,” said UN Secretary-General António Guterres.
NOAA’s Climate Prediction Center maintained an El Niño Advisory on August 13 and gave a greater than 90% probability of a very strong event during Northern Hemisphere fall and winter 2026–27.
NOAA reported July anomalies of +1.4°C (+2.5°F) in Niño 3.4, +1.7°C (+3.1°F) in Niño 3 and +2.9°C (+5.2°F) in Niño 1+2. Subsurface temperature anomalies reached +10°C (+18°F) at depth.
Low-level westerly wind anomalies and upper-level easterly wind anomalies extended from the western to east-central equatorial Pacific. Convection and rainfall were enhanced from the central to eastern Pacific and suppressed over Indonesia, indicating that the ocean and atmosphere were responding together as El Niño strengthened.
NOAA assigned a 69% probability that the three-month Relative Oceanic Niño Index (RONI) will reach at least +2.5°C (+4.5°F) during October–December 2026. The agency said that value would exceed previous El Niño events in its RONI record dating to 1950, but the threshold remains forecast rather than observed.
The Center for Climate Systems Research and International Research Institute for Climate and Society (CCSR/IRI) reported a traditional Niño 3.4 seasonal anomaly of +1.51°C (+2.72°F) for May–July, a July monthly anomaly of +2.03°C (+3.65°F) and a weekly value of +2.7°C (+4.9°F) centered on August 12. The CCSR/IRI values are not directly interchangeable with CPC’s operational values because the products use different SST datasets and index methodologies.
CCSR/IRI located subsurface temperature anomalies exceeding +8°C (+14.4°F) at depths of approximately 50–150 m (164–492 feet) across parts of the central-eastern equatorial Pacific.
In its August 19 assessment, 25 of 26 models placed Niño 3.4 in the very strong category for October–December 2026, defined as an anomaly of at least +2°C (+3.6°F). Fifteen models forecast anomalies of at least +3°C (+5.4°F).
WMO’s Global Seasonal Climate Update for September–November 2026 forecasts the seasonal-average Niño 3.4 SST ensemble-mean anomaly to reach approximately +3.6°C (+6.5°F), with the intensification trajectory expected to peak around November–December.
These model counts indicate the level of agreement among the forecasts and are not separate probability estimates.
Direct comparison between traditional Niño 3.4 SST anomaly measures and NOAA’s RONI forecast is limited because the products use different indices, datasets, averaging periods and climatological baselines.
The traditional Oceanic Niño Index (ONI) uses a three-month running mean of sea surface temperature anomalies within the Niño 3.4 region. RONI subtracts the mean tropical-ocean SST anomaly from the Niño 3.4 anomaly and then applies a variance adjustment, reducing the influence of broader tropical-ocean warming.
CCSR/IRI identifies its traditional Niño 3.4 measure as TONI, while NOAA’s Climate Prediction Center transitioned to RONI for official ENSO monitoring and prediction in February 2026.
WMO forecasts an increased likelihood of above-normal temperatures across almost all land areas during September–November 2026, accompanied by rainfall patterns associated with the strong Pacific El Niño.
A positive Indian Ocean Dipole is also forecast, with the Dipole Mode Index expected to average +0.9°C (+1.6°F) during September–November. Sea surface temperatures in the North and South Tropical Atlantic are forecast to remain above normal.
WMO said conditions in the Indian and Atlantic oceans could reinforce, weaken or modify El Niño-related regional patterns.
It is worth noting that El Niño strength alone does not determine the severity of weather impacts in an individual country or region. Its effects vary by location and season and can be influenced by other oceanic and atmospheric conditions.
References:
1 El Niño set to become very strong, raising risks of extreme weather into 2027 – WMO – September 3, 2026
2 ENSO Diagnostic Discussion – NOAA/CPC – August 13, 2026
3 Global Seasonal Climate Update for September-October-November 2026 – WMO – September 3, 2026
4 August 2026 Quick Look – CCSR/IRI – August 19, 2026
Rishav Kothari is Editor-in-Chief of The Watchers, where he runs the newsroom and covers earthquakes, volcanoes, severe weather and space weather.
