Maps from the National Aeronautics and Space Administration (NASA) show Pacific changes linked to El Niño; the National Oceanic and Atmospheric Administration (NOAA) gives an 83% chance the event will cross a strength benchmark tied to records since 1950.
NOAA’s Oct. 8 outlook assigns those odds to October through December 2026. It projects a three-month average of at least +2.5°C on the Relative Oceanic Niño Index (RONI), a threshold above the strength of events in NOAA’s record from 1950 onward. The 83% estimates the likelihood of meeting that test; it does not show that the threshold has already been reached. NOAA also reported September sea-surface temperature anomalies above +4.0°C in parts of the eastern equatorial Pacific.
NASA’s visualizations, released Oct. 15, compare the same months in 2025 and 2026. They show warm pulses known as Kelvin waves reaching the eastern Pacific in early April. The waves move heat from west to east. NASA says the warmer water then heats the air above it, changing pressure patterns that can weaken or reverse trade winds.
Ocean height was 30 to 40 centimeters above normal in some locations, while areas near Indonesia and northern Australia were 15 to 20 centimeters below normal. Sentinel-6 satellites measure ocean height worldwide every 10 days.
NASA’s PACE mission detected a bluer equatorial Pacific, which the agency associates with fewer phytoplankton. Weaker trade winds reduce the rise of nutrient-rich water from below, NASA said, with potential effects on the marine food web. PACE launched in 2024, making this the first El Niño the mission has observed, NASA said.
The World Meteorological Organization (WMO) forecasts a Niño-3.4 temperature anomaly of about +3.7°C for October through December, measured against a 1993-2009 baseline, with a peak near December. The WMO identified +2.6°C in November 2015 to January 2016 as the previous high. Its Niño-3.4 projection and NOAA’s RONI benchmark use different measures, so their figures are not directly comparable. The WMO also expects above-average temperatures in many regions and said changing rainfall patterns may increase drought and flood risks.
NOAA’s next ENSO Diagnostic Discussion is scheduled for Nov. 12.
