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: Not Active

 

Outlook: ENSO-neutral is most likely through the late Northern Hemisphere summer 2025 (56% chance in August-October). Thereafter, chances of La Nina conditions increase into the fall and winter 2025-26, but remain comparable to ENSO-neutral.

 

Discussion:

 

During June 2025, ENSO-neutral continued, with near-average sea surface temperatures (SSTs) prevailing across most of the equatorial Pacific Ocean (Fig. T18). The monthly Nino SST index values ranged from 0.0C to +0.6C (Table T2). Subsurface temperature anomalies were weakly positive and nearly unchanged from last month, with mostly above-average temperatures established along the thermocline (Fig. T17). Over the east-central and eastern equatorial Pacific Ocean, low-level wind anomalies were easterly and upper-level wind anomalies were westerly (Figs. T20 & T21). Convection remained enhanced over Indonesia (Fig. T25). Collectively, the coupled ocean-atmosphere system in the tropical Pacific reflected ENSO-neutral.

The IRI predictions indicate ENSO-neutral is most likely through the Northern Hemisphere winter 2025-26 (Figs. F1-F12). In contrast, the North American Multi-Model Ensemble favors the onset of La Nina conditions during the Northern Hemisphere fall, though lasting a shorter duration than NOAA’s requirement of five consecutive overlapping 3-month seasons. While the subsurface equatorial Pacific remains above average, easterly trade winds are predicted to strengthen in the coming month, which could portend cooler conditions. In summary, ENSO-neutral is most likely through the late Northern Hemisphere summer 2025 (56% chance in August-October). Thereafter, chances of La Nina conditions increase into the fall and winter 2025-26, but remain nearly equal to ENSO-neutral.

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