Research notes and updates from the team.
The observed SST anomaly in the NINO3.4 region during the Jan–Mar 2026 season was -0.25 °C, and for March 2026, it was +0.03 °C. The most recent weekly average (week centered on Apr 15, 2026) of the NINO3.4 index was +0.5 °C. These values indicate that Pacific sea-surface temperatures are in an ENSO-neutral state and are beginning to develop into El Niño.
Read more →The observed SST anomaly in the NINO3.4 region during the Dec–Feb 2026 season was -0.45 °C, and for February 2026, it was -0.20 °C. The most recent weekly average (week centered on March 11, 2026) of the NINO3.4 index was -0.0 °C. These values indicate that Pacific sea-surface temperature anomalies have weakened to ENSO-neutral levels.
Read more →The observed SST anomaly in the NINO3.4 region during the Nov–Jan 2026 season was -0.61 °C, and for January 2026, it was -0.54 °C. The most recent weekly average (week centered on February 11, 2026) of the NINO3.4 index was -0.2 °C. These values indicate that Pacific sea-surface temperature anomalies have been experiencing weak but declining La Niña conditions across the equatorial Pacific.
Read more →The observed SST anomaly in the NINO3.4 region during the Oct–Dec 2025 season was -0.59 °C, and for December 2025, it was -0.61 °C. The most recent weekly average (week centered on January 14, 2026) of the NINO3.4 index was -0.7 °C. These values indicate that Pacific sea-surface temperature anomalies have been experiencing weak La Niña conditions across the equatorial Pacific.
Read more →The SST anomaly in the NINO3.4 region during the Sep–Nov 2025 season was -0.53 °C, and for November, it was -0.68 °C. The most recent weekly average (week centered on December 10, 2025) of the NINO3.4 index was -0.7 °C.
Read more →The SST anomaly in the NINO3.4 region during the Aug–Oct 2025 season was -0.42 °C, and for October, it was -0.48 °C. The most recent weekly average (week centered on November 12, 2025) of the NINO3.4 index was -0.7 °C.
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