After a break of several months, La Niña returns to the equatorial Pacific. September 2025 and continued until December. However, this phenomenon ChildIts cooler counterpart is relatively weak, and its impact on weather and climate over the next few months remains to be seen.
Part El Niño-Southern Oscillation (ENSO), La Niña develops when stronger easterly trade winds increase the rise of cold, deep water in the eastern tropical Pacific Ocean. This process cools large areas of the eastern and central equatorial Pacific Ocean while pushing warm surface waters westward toward Asia and Australia. In a report released Dec. 11, NOAA's Climate Prediction Center confirmed that below-average sea surface temperatures associated with La Niña conditions are present and likely to persist for another month or two.
Changing wind patterns and the movement of heat in the ocean have a direct impact on sea levels. Because colder water is denser and takes up less volume than warmer water, sea levels in the central and eastern Pacific Ocean fall during La Niña events. The map above shows the sea surface height observed on December 1, 2025. Shades of blue indicate below-normal sea levels, shades of red indicate above-normal levels, and white indicates near-normal conditions.
Card data has been received Sentinel-6 Michael Freilich satellite and processed by scientists at NASA's Jet Propulsion Laboratory (JPL). Signals associated with seasonal cycles and long-term trends were removed to highlight sea level changes associated with ENSO and other short-term natural events. Satellite's twin successor, Guardian-6Blaunched in November 2025 and is expected to begin participating in ENSO research and forecasts sometime in 2026.
Cooling of equatorial surface waters changes the exchange of heat and moisture between the ocean and the atmosphere, changing shape. global atmospheric circulation patterns. La Niña's relationship with the ocean and atmosphere may change mid-latitude jet streamswhich increases rainfall in some regions, while bringing drought to others.
Typically, La Niña years have below average rainfall in the American Southwest and above average rainfall in the Northwest. But when the event is weak—whether El Niño or La Niña—the associated weather patterns can be “extremely difficult to predict,” said Josh Willis, an oceanographer and Michael Freilich Sentinel-6 project scientist at the Jet Propulsion Laboratory in Southern California.
“It still has the potential to tilt our winter toward drought in the American Southwest,” Willis said. “But that's never a guarantee, especially with something as mild as this.”
NASA Earth Observatory image by Lauren Dauphine using modified Copernicus Sentinel data (2025), processed by the European Space Agency, and further processed by Josh Willis and Kevin Marlies/NASA/JPL-Caltech. Story by Katherine Hansen.
Links and resources
- NASA Earth Observatory (2025) Child. As of December 15, 2025
- NASA Earth Observatory (February 6, 2025) The girl is here. As of December 15, 2025
- NASA Jet Propulsion Laboratory (2025) Ocean surface topography from space. As of December 15, 2025
- NOAA Climate Prediction Center (December 11, 2025) Diagnostic discussion of the El Niño/Southern Oscillation (ENSO). As of December 15, 2025
- World Meteorological Organization (4 December 2025) WMO update predicts weak La Niña. As of December 15, 2025
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