Above-average sea surface temperatures (SST) persisted across the equatorial Pacific Ocean, with the largest anomalies observed in the central and east-central Pacific [Fig. 1]. The latest weekly Niño index values remained at +1.4°C in Niño-4, +1.9°C in Niño-3.4, and +2.0°C in Niño-3, while Niño-1+2 weakened to +1.0°C [Fig. 2]. Area-averaged positive subsurface temperature anomalies decreased in December [Fig. 3], reflecting the strengthening and eastward expansion of below-average subsurface temperatures in the western Pacific [Fig. 4]. Over the east-central Pacific Ocean, low-level wind anomalies were westerly, while upper-level wind anomalies were easterly. Convection/rainfall remained enhanced at the Date Line and was suppressed around Indonesia [Fig. 5]. The equatorial and station-based SOI were negative. Collectively, the coupled ocean-atmosphere system reflected a strong and mature El Niño.

The most recent IRI plume indicates El Niño will gradually weaken and then transition to ENSO-neutral during spring 2024 [Fig. 6]. Some state-of the-art dynamical climate models suggest a transition to ENSO-neutral as soon as March-May 2024. The forecast team, however, delays this timing and strongly favors a transition to ENSO-neutral in April-June 2024. There are also increasing odds of La Niña in the seasons following a shift to ENSO-neutral. It is typical for El Niño to peak in December/early January, but despite weakening, its impacts on the United States could last through April (see CPC seasonal outlooks for probabilities of temperature and precipitation). In summary, El Niño is expected to continue for the next several seasons, with ENSO-neutral favored during April-June 2024 (73% 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). Additional perspectives and analysis are also available in an ENSO blog. A probabilistic strength forecast is available here. The next ENSO Diagnostics Discussion is scheduled for 8 February 2024.

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