National Weather Service Issues Official La Niña Advisory for 2025-26 Winter

A La Niña Advisory has been issued by the National Oceanic and Atmospheric Administration (NOAA) on Thursday, meaning that La Niña conditions have been observed in the tropical Pacific Ocean and are expected to continue through the December 2025 to February 2026 timeframe. La Niña is characterized by unusually cold ocean temperatures in the Equatorial Pacific, compared to its opposite El Niño, which is characterized by unusually warm ocean temperatures in the Equatorial Pacific. La Niña occurs when strong east-to-west trade winds along the equator push warm surface water toward the western Pacific, allowing cooler, nutrient-rich water to rise near South America—a process called upwelling. This leads to a sustained drop in sea surface temperatures of at least 0.5 °C below normal across the eastern Pacific, which defines the event.

• Related: NOAA: “What Is La Niña?”

Typically lasting 9 to 12 months and recurring every 2 to 7 years, La Niña influences global weather patterns in distinctive ways: colder, wetter winters in the U.S. Northwest and northern Plains (meaning more snow), and drier, warmer winters across the South; wetter-than-average conditions in Australia and Southeast Asia; and drier climates in western South America and East Africa, while southern Africa tends to see more rainfall.

According to the official advisory, La Niña conditions are present and favored to persist through December 2025 to February 2026, with a transition to ENSO-neutral likely in January-March 2026 (55% chance). The full advisory is attached below, courtesy of NOAA.

La Niña conditions emerged in September 2025, as indicated by the expansion of below-average sea surface temperatures (SSTs) across the central and eastern equatorial Pacific Ocean [Fig. 1]. The latest weekly Niño-3.4 index value was -0.5°C, with other regions remaining at or between -0.1°C and -0.4°C [Fig. 2]. Negative subsurface temperature anomalies persisted (averaged from 180°-100°W; [Fig. 3]), with below-average temperatures prevailing from the surface to 200m depth in the eastern half of the equatorial Pacific [Fig. 4]. Over the western and east-central equatorial Pacific, low-level wind anomalies were easterly and upper-level wind anomalies were westerly. Convection continued to be enhanced over Indonesia and was suppressed near the Date Line [Fig. 5]. The equatorial Southern Oscillation index was positive. Collectively, the coupled ocean-atmosphere system reflected La Niña conditions.

The IRI multi-model predictions favor La Niña through the Northern Hemisphere winter 2025-26 [Fig. 6]. The North American Multi-Model Ensemble is also in agreement, and based on recently observed anomalies, the team favors La Niña to continue through winter. At this time, La Niña is expected to remain weak (3-month average Niño-3.4 index value at or between -0.5°C and -0.9°C). A weak La Niña would be less likely to result in conventional winter impacts, though predictable signals could still influence the forecast guidance (e.g., CPC’s seasonal outlooks). In summary, La Niña conditions are present and favored to persist through December 2025 – February 2026, with a transition to ENSO-neutral likely in January-March 2026 (55% chance; [Fig. 7]).

This discussion is a consolidated effort of the National Oceanic and Atmospheric Administration (NOAA), NOAA’s National Weather Service, and their funded institutions. Oceanic and atmospheric conditions are updated weekly on the Climate Prediction Center web site (El Niño/La Niña Current Conditions and Expert Discussions). A probabilistic strength forecast is available here. The next ENSO Diagnostics Discussion is scheduled for 13 November 2025.

For more information visit cpc.ncep.noaa.gov.

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