ENSO-neutral conditions remain in place, and there is a 60% chance that ENSO-neutral conditions will continue during August-October 2025, followed by a 55% chance that ENSO-neutral will remain in place during September-November.
As of 21 July 2025, the 30-day NINO3.4 Index (in the central equatorial Pacific) was +0.02˚C, in the neutral range. The 30-day relative Niño 3.4 Index (RONI) was -0.28˚C, reflective of the central equatorial Pacific being cooler than the average of the global tropics and on the La Niña side of neutral.
The Southern Oscillation Index (SOI) was on the La Niña side of the neutral range during May-July (+0.7), while the July value was also +0.7 (on the La Niña side of the neutral range).
Temperatures in the subsurface equatorial Pacific are generally above average in the western part of the basin with cooler than average temperatures developing in the east. Should these cooler temperatures in the east reach the surface in the coming months, it could push ENSO in a La Niña direction.
Upper oceanic heat content continues to indicate ENSO-neutral conditions.
The South Pacific Convergence Zone (SPCZ) was located close to its climatological normal position during July.
During August-October, model guidance favours an enhancement in convective forcing over the western Pacific and Melanesia, collocated with the warmest sea surface temperatures. This may lead to enhanced rainfall for island groups such as Palau and Papua New Guinea east to Fiji and Tonga.
However, drier than normal conditions are likely to occur for most island groups along and north of the equator, including the Federated States of Micronesia, the Marshall Islands, Nauru, Kiribati, Tuvalu, Tokelau, and parts of French Polynesia (see pages 6-7 for more information).
