The ocean and atmosphere are in a weak La Niña state that will likely be brief, primarily focused on the central Pacific (i.e., La Niña “Modoki”). There is a 35% chance that La Niña will continue through March-May 2025 and a 65% chance that ENSO-neutral conditions will return.
As of 17 February, the 30-day NINO3.4 Index (in the central equatorial Pacific) was -0.65˚C, slightly in the La Niña range. The 30-day relative Niño 3.4 Index (RONI) was -1.20˚C, reflective of the central equatorial Pacific being significantly cooler than the average of the global tropics.
The Southern Oscillation Index (SOI) was in the La Niña range during December-February (+0.6), while the February value was +1.0 (in the La Niña range).
The subsurface equatorial Pacific is 2˚C to 4˚C cooler than average just below the surface in the east of the basin, while above average upper oceanic heat content continues in western parts of the Pacific basin, which is a La Niña signature
The South Pacific Convergence Zone (SPCZ) was located well south of its climatological normal position during February.
During March-May, model guidance favours an enhancement in convective forcing over the western Pacific and Maritime Continent, consistent with La Niña-like patterns. This may lead to enhanced rainfall for some island groups such as Palau, Guam, Northern Marianas, Federated States of Micronesia, Marshall Islands, and southern Papua New Guinea east to Niue. However, drier than normal conditions are likely to persist for island groups along the equator (see pages 6-7 for more information).
Tropical cyclone season continues through April 2025. Tropical cyclone chances may be greatest in the Southwest Pacific through early March with cyclone chances increasing again in late March as a pulse of the Madden-Julian Oscillation (MJO) enters the western Pacific.
