Satellite data suggest 2026 El Niño could rival or exceed the strong 1997-98 event
NASA Earth Observatory compared sea level maps from 1997 and 2026 and found similar patterns, but a NASA scientist says the effects this winter are still uncertain.
This year's El Niño may grow bigger than the very strong event of 1997-98, according to NASA Earth Observatory. Its report compares satellite measurements of sea surface height across the Pacific Ocean.
The comparison uses a 35-year record from altimetry satellites, which measure the height of the sea surface. Water expands as it warms, so sea levels that are higher than normal in the central and eastern equatorial Pacific show the build-up of heat linked to El Niño. NASA Earth Observatory published maps of sea level anomalies from October 13, 1997, and October 12, 2026. The data came from the TOPEX/Poseidon and Sentinel-6 Michael Freilich satellites and were processed by scientists at NASA's Jet Propulsion Laboratory (JPL).
“That lets us look back in time and compare this El Niño to what happened in 1997. And right now, this one is on track to be even bigger.”Josh Willis, project scientist for sea level missions at JPL
The report says the 2026 El Niño developed much more suddenly than the 1997-98 event. As of October, though, the two look alike. In both, sea level is low in the west and high in the east, and high, warm water stretches all the way to South America. Willis thinks the effects could also be similar. In 1997-98, that meant heavy rain in California and across the southern U.S., according to the report.
The comparison matters because of what earlier strong events did. NASA Earth Observatory says the very strong El Niños of 1997-98 and 2015-16 disrupted weather patterns around the world. Their effects included fires in Indonesia and the Amazon, crop failures from drought in southern Africa, and heavy rain and coastal flooding in Southern California.
Each event is different, the report notes. In 2015, the unusually warm, high water along the equator did not push against South America as much as it did in 1997 and 2026. That winter, most of the extra rain fell over Central America and the southeastern U.S., and Mexico saw serious flooding.
Citing an outlook from the U.S. National Oceanic and Atmospheric Administration (NOAA) issued on October 8, 2026, NASA Earth Observatory reported an 83 percent chance of a strong to very strong El Niño through the first three months of 2027.
How this El Niño will affect weather in winter 2026-27 and later is not yet known, according to the report. Willis said El Niño's influence travels through a chaotic atmosphere, and the signal can become muddled as it reaches beyond the tropics.
"There's always a bit of a dice roll here," Willis said. He added that a resemblance to 1997 does not mean this event will play out the same way, calling the comparison "just our best guess at the moment."
This story is based on a single report from NASA Earth Observatory.
