The Risk of 97L Strengthening and Eventually Becoming an East Coast Problem Increasing
08/11/2025, 8:58 am EDT
Climate Impact Company Weekly ENSO Climate Diagnostics
Issued: Monday August 11, 2025
Highlight: The equatorial Pacific surface/subsurface has cooled slightly but neutral ENSO prevails; ECMWF forecasting El Nino by spring 2026.
Discussion: During mid-July to early August, the surface and subsurface equatorial Pacific Ocean east of the Dateline cooled slightly. However, neutral ENSO prevails. The Nino34 SSTA is -0.3C not far from the La Nina threshold (Fig. 1). Southern oscillation index (SOI) has varied recently and favors neutral ENSO continuing. There remains some potential for La Nina to regenerate during Q4/2025 if the equatorial Pacific subsurface continues to cool. The risk is low, about 25-30%. Interestingly, ECMWF has shifted their Nino34 SSTA forecast to El Nino by MAR/APR/MAY 2026 (Fig. 2). ECMWF is the only forecaster, for now, with the El Nino risk. Since the 2015-16 El Nino episode, ENSO has fluctuated between weak La Nina and weak El Nino looks and that trend seems to be continuing.
Fig. 1: The 12-week monitor of the Nino SSTA regions indicates a slight cooler shift of the Nino34 SSTA region.
Fig. 2: ECMWF Nino34 SSTA forecast shifts to El Nino in 2026.