NASA: 2026 El Niño Driving Exceptional Pacific Warming, Sea-Level and Biological Shifts

NASA said Thursday that satellite observations show the 2026 El Niño is already driving unusually large changes across the Pacific, with exceptional warming in surface waters, sharp shifts in sea level and visible changes in ocean biology.

Those observations align with forecasts from the National Oceanic and Atmospheric Administration and the World Meteorological Organization that the event is likely to rank among the strongest on record by key official measures. But that “historic” label remains a forecast-based characterization, not a final confirmed ranking. NOAA also changed this year to a newer operational index, called the Relative Oceanic Niño Index, or RONI, meaning comparisons with events such as 1982-83, 1997-98 and 2015-16 depend partly on which index is used.

In a report published Oct. 15, NASA said sea surface temperatures in the eastern Pacific are about 3 degrees Fahrenheit, or 1.7 degrees Celsius, above the long-term average. The agency said eastward-moving pulses of warm water known as Kelvin waves reached the eastern Pacific by early April, helping heat the surface and lift sea level there. “Kelvin waves are like the heartbeat of El Niño,” said Josh Willis, project scientist for sea level missions at NASA’s Jet Propulsion Laboratory.

NASA said satellite altimeters show that in some parts of the eastern Pacific, local sea level rose by about 1 to 1.3 feet, or 30 to 40 centimeters. At the same time, sea level around Indonesia and northern Australia was about 6 to 8 inches, or 15 to 20 centimeters, below normal. NASA said the sea-level record from satellite altimetry has run continuously since 1993.

The agency is also tracking how the event is changing the ocean’s surface biology. Data from NASA’s PACE mission, which measures ocean color from space, showed the equatorial Pacific becoming bluer. That is consistent with reduced phytoplankton — the microscopic marine organisms at the base of the food web — and weaker upwelling, the normal rise of cold, nutrient-rich water to the surface that is often suppressed during El Niño. “Some people think of water as being just blue, but it’s amazing the multitude of colors the ocean can be,” said Matthew Kehrli, PACE lead research scientist at NASA.

NOAA’s Climate Prediction Center said in its Oct. 8 ENSO Diagnostic Discussion that El Niño “continues to strengthen.” It reported readings of about plus-2.1 C in the Niño-3.4 region, plus-3.0 C in Niño-3 and plus-3.9 C in Niño-1+2, with sea-surface temperature anomalies exceeding plus-4.0 C in parts of the eastern equatorial Pacific. Using NOAA’s RONI threshold for a “historic” event — a three-month average of at least plus-2.5 C — the agency put the odds at 54% for September-October-November, 83% for October-November-December and 70% for November-December-January.

The World Meteorological Organization said Oct. 8 that El Niño is “firmly established and strengthening rapidly.” It forecast the October-November-December Niño-3.4 anomaly near plus-3.7 C and said the event is near 100% likely to persist through February 2027.

El Niño is a natural climate pattern that develops every two to seven years when waters in the equatorial Pacific become warmer than normal, reshaping weather patterns around the world. NOAA and the WMO say strong events typically bring heavier rain and storms to parts of South America and the southern United States, drier conditions and higher drought risk in Indonesia, Australia and parts of southern Asia, a greater risk of coastal high-tide flooding along the U.S. West Coast, and reduced Atlantic hurricane activity while boosting storm activity in the central and eastern Pacific.