Three Satellite Views of the 2026 El Niño: Height, Heat and Ocean Colour

NASA says its fleet of Earth-observing satellites is watching the 2026 El Niño from three different angles at once — the height of the sea surface, its temperature, and its colour — in an article published on 15 October 2026 by writers Erica McNamee and Sally Younger. The agency noted that as of October, the National Oceanic and Atmospheric Administration has put the odds at 83% that the strongest El Niño since 1950 is currently under way.

NASA describes El Niño as a natural climate pattern that appears roughly every two to seven years, marked by warmer-than-normal water in parts of the equatorial Pacific. The agency says scientists are tracking how it flips trade winds, redistributes ocean heat, scrambles rainfall patterns and raises sea surface height across parts of the Pacific, with farmers, firefighters and coastal communities already feeling the effects in different ways.

A Kelvin wave, then a rise in sea level

According to NASA, one of the first clues came in satellite imagery from January 2026, when a swell of warm water known as a Kelvin wave was spotted near Micronesia in the western Pacific. The agency describes these waves as slow-moving pulses thousands of miles long that act like underwater freeways, carrying heat from west to east. Warm water heats the air above it, that air rises, and the resulting pressure change weakens or reverses the trade winds — a chain reaction NASA says marks the onset of an El Niño.

By early April, NASA says, those Kelvin waves had arrived in the eastern Pacific and sea surface temperatures were beginning to climb. Because warm water expands, local sea levels in some areas have been lifted by as much as 1 to 1.3 feet (30 to 40 centimetres), visible in the agency's maps as higher-than-normal water moving toward South America and then north along the coast to California. At the other end of the basin, NASA reports sea levels 6 to 8 inches (15 to 20 centimetres) below normal around Indonesia and northern Australia.

"Kelvin waves are like the heartbeat of El Niño," said Josh Willis, project scientist for sea level missions at NASA's Jet Propulsion Laboratory. "And our sea level satellites let us peer into the ocean and watch every beat."

The agency notes that satellite altimetry has tracked ocean height since 1993, a record now continued by the Sentinel-6 satellites, which measure water height across the entire ocean every 10 days down to fractions of an inch. NASA says their radar altimeters survey millions of square miles of ocean in a single day, complementing NOAA's buoys and ocean sensors.

Warmer water, and a bluer ocean

On temperature, NASA says sea surface temperatures in the eastern Pacific are already about 3 degrees Fahrenheit (1.7 degrees Celsius) warmer than the long-term average, and Willis said they could rise another fraction of a degree in the coming months. The agency's maps show a band of warmer-than-normal water expanding through the spring and stretching millions of square miles from the central Pacific to the South American coast.

The third view comes from colour. NASA says equatorial Pacific waters have become measurably more blue over recent months, a change it attributes to declining phytoplankton. Weakening trade winds reduce the upwelling of nutrient-rich deep water, the agency explains, cutting the food supply for the microscopic plants at the base of the marine food web and potentially forcing other marine life to relocate.

"Some people think of water as being just blue, but it's amazing the multitude of colors the ocean can be," said Matthew Kehrli, a lead research scientist for the PACE satellite team at NASA's Goddard Space Flight Center.

NASA says this is the first El Niño observed since PACE launched in 2024. Its Ocean Color Instrument views the ocean in hyperspectral colour across several hundred wavelengths of visible, near-infrared and ultraviolet light, from which researchers derive a single summary number called apparent visible wavelength. The agency's comparison maps show the green band along the equatorial western Pacific shrinking in 2026 as blue fills in, while the same region held steady in 2025, which NASA describes as a weak La Niña year.

NASA says its scientists will keep monitoring the event. "El Niño touches almost all of us in some way every time it occurs," Willis said. "While many have seen what it can do, we look to the ocean to understand why." The full article and visualisations are available from NASA. More background on measurement methods is available on our science page.