Recent Rapid Warming of Nino SSTA Regions Eases

Fig. 1: The 12-week Nino region(s) weekly SSTA tracker reveals the recent warming has leveled off.

Discussion: The warming of the Nino SSTA regions ending La Nina and suggesting a possible El Nino (very warm Nino12 SSTA) evolution has leveled off during the past 2-3 weeks (Fig. 1). Neutral ENSO is steady. Weak or non-existent trade winds to up-well cool waters are starting to regenerate as the southern oscillation index (SOI) shifts to a mostly positive phase during the past 30 days (Fig. 2). The upper ocean heat anomalies favoring La Nina weakened sharply during the past two months, especially off the northwest coast of South America (Fig. 3). The warm upper ocean heat anomalies have cooled slightly in April as +SOI and trade winds have re-emerged. The latest CFS V2 Nino34 SSTA forecast consensus is neutral phase for 2025 although ensemble members of the forecast vary widely from weak El Nino to weak La Nina (Fig. 4).  

Fig. 2: The daily southern oscillation index has shifted to mostly positive during the past 30 days.

Fig. 3: The persistent cool anomalies in the upper ocean east of the Dateline fades during the past 2 months.

Fig. 4: The latest CFS V2 Nino34 SSTA forecast reveals a consensus neutral ENSO outlook for 2025.