Data from the international Sentinel-6 Michael Freilich satellite has captured a warm Kelvin wave moving across the Pacific Ocean toward the South American coast, signaling that an El Niño event is likely to follow, NASA has announced.

Sea-level height measurements collected between March and May 2026 show higher, warmer water moving from the western Pacific to waters off the coast of Colombia, Ecuador and Peru. By mid-May, seas around Peru were more than 15cm above long-term averages. Because water expands as it warms, a rise in ocean surface elevation indicates increasing temperature.

An earlier, smaller Kelvin wave had formed around Micronesia in late January 2026 before dissipating by mid-February. The wave captured in the latest data emerged in early March and moved eastward over the following weeks.

The additional heat at the sea surface can alter atmospheric circulation patterns, affecting energy, water and air in the atmosphere, with knock-on effects for weather across the globe. El Niño events are associated with heavy precipitation in some regions and deficits in others, with wide-ranging impacts on daily life and commerce.

Sentinel-6 Michael Freilich – named after the former NASA Earth Science Division director – is one of two satellites that make up the Copernicus Sentinel-6/Jason-CS (Continuity of Service) mission. The mission was jointly developed by ESA, the European Organisation for the Exploitation of Meteorological Satellites (EUMETSAT), NASA and NOAA, with funding support from the European Commission and technical support from CNES, the French space agency.

Spacecraft monitoring, control and altimeter science data processing are carried out by EUMETSAT on behalf of the European Union’s Copernicus program, supported by all partner agencies.

NASA’s Jet Propulsion Laboratory, a division of Caltech in Pasadena, contributed three science instruments to each Sentinel-6 satellite: the Advanced Microwave Radiometer, the Global Navigation Satellite System – Radio Occultation, and the Laser Retroreflector Array. NASA also provided launch services, ground systems to support operation of its science instruments, science data processors for two of those instruments, and support for US members of the international Ocean Surface Topography Science Team.

In related news, WMO warns El Niño is developing with 80% certainty, urges preparation