A phenomenon rarer than a solar eclipse and more powerful than any single storm system is unfolding this fall, and NASA is tracking it closely. El Niño is a natural climate pattern that emerges roughly every two to seven years, marked by warmer-than-normal water temperatures in parts of the equatorial Pacific. NASA scientists are keeping watch as it flips trade winds, redistributes ocean heat, scrambles rain patterns, and raises sea surface height across parts of the ocean.
As of October, NOAA has said there is an 83% chance that the strongest El Niño since 1950 is currently unfolding. People around the world, including farmers, firefighters, and coastal communities, are already experiencing the effects in different ways.
One of the first clues appeared in satellite imagery in January 2026, when a swell of warm water called a Kelvin wave was spotted near Micronesia in the western Pacific. Kelvin waves are slow-moving pulses of water thousands of miles long that transfer heat from west to east across the Pacific. By early April, those Kelvin waves had reached the eastern Pacific, and sea surface temperatures had begun to warm. Warm water expands in volume, elevating local sea levels in some areas by as much as 1 to 1.3 feet (30 to 40 centimeters). The higher-than-normal water can be seen sloshing toward South America then moving up the coast to California. Meanwhile, sea levels six to eight inches (15 to 20 centimeters) lower than normal are visible around Indonesia and northern Australia.
NASA's Scientific Visualization Studio has released maps comparing ocean data from 2025 (a weak La Niña year) and 2026, using altimetry data from the Sentinel-6 satellites, which measure water height for the entire ocean every 10 days down to fractions of an inch. The visualizations show the stark contrast between the two years.