Forecast Forum

The canonical correlation analysis (CCA) forecast of SST in the central Pacific (Barnett et al. 1988, Science, 241, 192‑196; Barnston and Ropelewski 1992, J. Climate, 5, 1316‑1345), is shown in Figs. F1 and F2. This forecast is produced routinely by the Prediction Branch of the Climate Prediction Center. The predictions from the National Centers for Environmental Prediction (NCEP) Coupled Forecast System Model (CFSv2) are presented in Figs. F3 and F4a, F4b. Predictions from the Markov model (Xue, et al. 2000: J. Climate, 13, 849‑871) are shown in Figs. F5 and F6. Predictions from the latest version of the LDEO model (Chen et al. 2000: Geophys. Res. Let., 27, 2585‑2587) are shown in Figs. F7 and F8.  Predictions from the ENSO‑CLIPER statistical model (Knaff and Landsea 1997, Wea. Forecasting, 12, 633‑652) are shown in Fig. F9. Nino 3.4 predictions are summarized in Fig. F10, provided by the Forecasting and Prediction Research Group of the IRI.

The CPC and the contributors to the Forecast Forum caution potential users of this predictive information that they can expect only modest skill.

 

ENSO Alert System Status: La Nina Advisory

 

Outlook: La Nina persists, followed by a 75% chance of a transition to ENSO-neutral during January-March 2026. ENSO-neutral is likely through at least Northern Hemisphere late spring 2026.

 

Discussion:

 

In December 2025, La Nina was reflected in the continuation of below-average sea surface temperatures (SSTs) across the east-central and eastern equatorial Pacific Ocean (Fig. T18). The monthly Nino-3.4 index value was -0.6C, with the Nino-3 index remaining cooler at -0.7C (Table T2). The equatorial subsurface temperature index (average from 180-100W) became slightly positive, reflecting the expansion of above-average temperatures from the western to the east-central Pacific at depth (Fig. T17). Atmospheric anomalies across the tropical Pacific Ocean remained consistent with La Nina. For most of the month, easterly wind anomalies were present over the central equatorial Pacific, and upper-level westerly wind anomalies continued across the equatorial Pacific (Figs. T20 & T21). Enhanced convection persisted over Indonesia and suppressed convection strengthened near the Date Line (Fig. T25). The equatorial Southern Oscillation index was positive (Fig. T2). Collectively, the coupled ocean-atmosphere system remains consistent with La Nina.

The IRI multi-model predictions indicate ENSO-neutral will emerge during January-March (JFM) 2026 (Figs. F1-F12). In conjunction with the North American Multi-Model Ensemble, the team favors ENSO-neutral to develop during JFM 2026. Even after equatorial Pacific SSTs transition to ENSO-neutral, La Nina may still have some lingering influence through the early Northern Hemisphere spring 2026 (e.g., CPC's seasonal outlooks). For longer forecast horizons, there are growing chances of El Nino, though there remains uncertainty given the lower accuracy of model forecasts through the spring. In summary, La Nina is favored to continue for the next month or two, with a transition to ENSO-neutral most likely in January-March 2026 (68% chance).

Weekly updates of oceanic and atmospheric conditions are available on the Climate Prediction Center homepage (El Nino/La Nina Current Conditions and Expert Discussions).