The cool cycle of the Pacific decadal oscillation has strengthened during recent years and will reach 30 years in duration if continued through 2026 as forecast by the Climate Impact Company constructed analog prediction. The 30-year duration matches the previous longest cool cycle observed during the middle 1940’s to middle 1970’s. Are we due for a long-term cycle change of the PDO?

While the potential for El Nino development seems to be developing, the statistical and dynamic forecast models are only partially indicating weak El Nino potential and include a slight risk of weak La Nina returning later in 2025 while the consensus forecast is neutral ENSO through 2025. However, evidence to support El Nino return in 2026 is increasing.

During FEB/MAR 2025, the upper ocean heat anomalies across the equatorial Pacific Ocean warmed dramatically (Fig. 1). The dramatic warming followed a cool peak in support of the 2024-25 La Nina episode.

Of potential influence on the 2025 North Atlantic tropical cyclone season is the ongoing very warm Nino12 SSTA off the northwest coast of South America while the Nino34 SSTA, where oceanic ENSO phase is measured, has recently shifted from La Nina to neutral ENSO although waters in this region have re-cooled slightly during the past 2 weeks. The persistent unusual warming of waters off the northwest coast of South America while the remainder of the equatorial East Pacific observed near normal SSTA began in early February.