La Niña conditions currently remain in place in the tropical Pacific, but La Niña is likely to dissipate in the coming months. There is about a 70% chance that La Niña will dissipate to ENSO-neutral during January-March 2026, with an 85% chance for ENSO-neutral conditions during February-April 2026.
As of 15 December 2025, the 30-day NINO3.4 Index (in the central equatorial Pacific) was -0.68˚C, near the La Niña range. The 30-day relative Niño 3.4 Index (RONI) was -0.94˚C, in the La Niña range and reflective of the central equatorial Pacific being cooler than the average of the global tropics.
The Southern Oscillation Index (SOI) was on the La Niña side of the neutral range during September-November (+0.8), while the November value was +1.2 (in the La Niña range).
Subsurface ocean temperatures in the equatorial Pacific remain above average in the western part of the basin with cooler than average temperatures in central and eastern areas.
Notably cooler than average temperatures are currently located in the central and eastern equatorial Pacific at depths of 50-150 metres. These cool water temperatures indicate a tropical Pacific in a La Niña state. However, warmer than average temperatures below 150 metres are progressing farther east.
During January-March, model guidance favours an enhancement in convective forcing over Micronesia and parts of Melanesia consistent with La Niña and co-located
with the warmest sea surface temperatures. This may lead to enhanced rainfall for island groups such as Palau, the Northern Marianas, and Federated States of Micronesia, as well as southern Papua New Guinea east to Tonga.
Conversely, drier than normal conditions are likely to occur for most island groups near the equator, including Kiribati, Tuvalu, Tokelau, northern Cook Islands, and French Polynesia (see pages 6-7 for more information).
Tropical cyclone season in the southwest Pacific is underway and continues through April 2026.
