Research notes and updates from the team.
The SST anomaly in the NINO3.4 region during the Jul–Sep 2025 season was -0.28 °C, and for September, it was -0.44 °C. The most recent weekly average (week centered on October 15, 2025) of the NINO3.4 index was -0.6 °C.
Read more →The Dipole Mode Index for the month of September was -0.71 °C, indicative of the presence of negative IOD conditions in the Indian Ocean. According to the CCSR@NASA-GISS/IRI’s criteria for defining positive and negative Indian Ocean Dipole (IOD) events, a positive IOD is classified when the DMI exceeds +0.4 °C, and a negative IOD when it falls below −0.4 °C.
Read more →During September 2025, sea surface temperature (SST) anomalies remained within the ENSO-neutral range over the central-eastern equatorial Pacific Ocean, with the monthly Niño 3.4 anomaly index at -0.44 °C.
Read more →The SST anomaly in the NINO3.4 region during the Jun–Aug 2025 season was -0.12 °C, and for August, it was -0.33 °C. The most recent weekly average (week centered on September 10, 2025) of the NINO3.4 index was -0.5 °C. While these values remain within the ENSO-neutral range, they reflect a clear cooling trend, indicating that cold conditions are gradually developing in the tropical Pacific Ocean.
Read more →The forecast shows a strong model consensus toward a negative IOD event during the boreal fall and early winter. For September and October, the probability of a negative IOD is near or at 100%. This high confidence persists through November, where the probability remains above 75%, while neutral and positive phases are comparatively unlikely.
Read more →During August 2025, sea surface temperature (SST) anomalies remained in the ENSO-neutral range over the central-eastern equatorial Pacific Ocean, with the monthly NINO3.4 anomaly index value at -0.33 °C. Weekly-averaged SST anomalies in the NINO3.4 region were -0.5 °C for the week centered on September 10, 2025.
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