Today’s Image of the Day from NASA Earth Observatory features La Niña, a global climate event that is expected to be short-lived.

The map represents sea surface height anomalies on January 13, 2025 across the central and eastern Pacific Ocean. 

“Shades of blue indicate sea levels that were lower than average, while shades of red indicate areas where the ocean stood higher than normal. Normal sea level conditions appear in white,” noted NASA.

The onset of La Niña 

According to the National Oceanic and Atmospheric Administration (NOAA), sea surface temperatures in the east-central equatorial Pacific dropped below average in December 2024, marking the onset of La Niña. This cooling pattern has persisted into early 2025.

NOAA’s Climate Prediction Center indicates a 59% chance that La Niña conditions will continue through February-April 2025, with a likely transition to ENSO-neutral conditions during March-May 2025.

“After seven months of waiting, La Niña – the cooler sister of El Niño – finally showed up in the eastern Pacific Ocean in early December 2024. La Niña may not stick around long, though,” said NASA.

What is La Niña?

La Niña is a phase of the El Niño-Southern Oscillation (ENSO) cycle that occurs when strengthened easterly trade winds enhance the upwelling of cooler water from the depths of the eastern tropical Pacific. 

This process leads to a significant cooling of surface waters in the central and eastern Pacific near the equator. The intensified trade winds also drive warm equatorial waters westward toward Asia and Australia. 

“This dramatic cooling of the ocean’s surface layers affects the atmosphere by modifying the moisture content across the Pacific,” explained NASA.

“In a report published on January 9, 2025, the NOAA Climate Prediction Center confirmed that La Niña conditions were present. They measured sea surface temperatures 0.7 degrees Celsius (1.3 degrees Fahrenheit) below average in an area of the tropical Pacific, from 170° to 120° West longitude, known as the Niño 3.4 region.”

“The signature of La Niña is also visible in the central and eastern Pacific Ocean as areas of lower-than-average water levels. That’s because cooler water contracts, lowering sea levels. (Conversely, warmer water expands, raising them).” 

La Niña forecast 

Josh Willis, an oceanographer and Sentinel-6 Michael Freilich project scientist at JPL, pointed out that although La Niña is here, it’s not a particularly strong one.

Willis noted that during an especially strong La Niña in 2010-2011, temperatures in the tropical Pacific were about 1.6°C (2.9°F) below average in January 2011, compared to just 0.7°C (1.3°F) below average in January 2025. 

NOAA predicts that this La Niña will remain weak and is unlikely to drop below -1°C from the average – the threshold for a moderate-strength event. Neutral conditions are expected to return during the meteorological spring.

La Niña’s interaction between the ocean and atmosphere alters global atmospheric circulation, shifting mid-latitude jet streams in ways that can intensify rainfall in some regions and cause drought in others. 

In the western Pacific, Indonesia and Australia may experience increased rainfall. The central and eastern Pacific is expected to experience reduced cloud cover and precipitation, leading to drier conditions in Brazil, Argentina, and other parts of South America. Meanwhile, Central America may see wetter conditions. 

In North America, La Niña typically brings cooler, stormier weather to the Pacific Northwest, while the southern United States and northern Mexico tend to experience warmer, drier conditions.

Natural source of variability

“ENSO adds a natural source of year-to-year variability in global temperatures. Because such a wide swath of the Pacific is cold, La Niña tends to keep a lid on the average global surface temperature,” explained NASA.

“But even the cool water in the Pacific does not completely offset long-term warming trends; some of the hottest years on record have coincided with La Niña, such as in 2010 and 2020.”

The map is based on data that was acquired by the Sentinel-6 Michael Freilich satellite and processed by scientists at NASA’s Jet Propulsion Laboratory (JPL). 

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