ENSO-neutral continued this past month, indicated in the mostly near average sea surface temperatures (SSTs) across the east-central and eastern equatorial Pacific Ocean [Fig. 1]. The most recent weekly Niño-3.4 index was +0.3°C, while SST anomalies remained cooler in the eastern Niño-3 region (-0.1°C) and warmer in the western Niño-4 region (+0.5°C; [Fig. 2]). Below-average subsurface temperatures weakened during the past month (area-averaged index in [Fig. 3]), but negative anomalies still dominated the eastern half of the Pacific [Fig. 4]. Low-level wind anomalies were easterly over the western equatorial Pacific, and upper-level winds were westerly over the eastern Pacific. Convection was near average around Indonesia and the Date Line [Fig. 5]. Collectively, the coupled ocean-atmosphere system reflected ENSO-neutral.

Compared to the previous month, the most recent IRI plume delayed the emergence of La Niña to September-November 2024, with La Niña then persisting through the Northern Hemisphere winter [Fig. 6]. The forecast team is also favoring a delayed development of La Niña this month, but is anticipating the transition to occur earlier (August-October). This is, in part, supported by the continuation of below-average subsurface ocean temperatures and near-term forecasts suggesting a resurgence of easterly wind anomalies in July. In summary, ENSO-neutral is expected to continue for the next several months, with La Niña favored to emerge during August-October (70% chance) and persist into the Northern Hemisphere winter 2024-25 (79% chance during November-January; [Fig. 7]).