Neutral ENSO Continues; Wildly Uncertain Forecasts!

Climate Impact Company Weekly ENSO Climate Diagnostics

Issued: Tuesday May 27, 2025

Highlight: Neutral ENSO continues; Wildly uncertain forecasts!

Fig. 1: The latest NCEP CFS V2 Nino34 SSTA forecast reveals a wide range of solutions for later this year!

Discussion: ENSO is in neutral phase as mid-year approaches. The outlook for later this year is uncertain. In fact, the latest NCEP CFS V2 Nino34 SSTA forecast reveals a range of ENSO phase possibilities ranging from strong El Nino to strong La Nina or continuation of neutral phase for the last third of 2025 (Fig. 1). The latest 8 ensemble members (blue) favor a La Nina solution. The upper ocean heat in the equatorial Pacific Ocean to the east of the Dateline often foreshadows any ENSO phase change. Currently, the upper ocean heat anomalies are slightly warmer than normal east of the Dateline and the cool fuel for La Nina of earlier this year and 2024 has clearly dissipated (Fig. 2). The Nino SSTA regions maintain a neutral ENSO signature although the Nino3 region in the eastern equatorial Pacific cooled to near the La Nina threshold last week (Fig. 3).

Fig. 2: The equatorial Pacific Ocean upper ocean heat anomalies from the past 12 months.

Fig. 3: The Nino SSTA regions 12-week monitoring identifying persistent neutral phase.