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In September 2025, the sea surface temperature (SST) anomaly map (top left) generally shows a cooling pattern in the central and eastern equatorial Pacific, consistent with the recent cooling SST trend observed in previous weeks.

Warm SST anomalies were present in the Philippine Sea, as well as in both the monitored northern and southern regions of the Tripole Pacific Index (TPI). Meanwhile, most parts of the North Pacific were considerably warmer, indicative of a negative PDO.

In the Indian Ocean, warmer SST anomalies are observed in the tropical eastern Indian Ocean (i.e., EIO), while cooler SST anomalies were present in the western Indian Ocean (i.e., WIO), reflecting a considerable negative dipole pattern. In general, the tropical Indian Ocean-wide SST anomalies (i.e., IOBW) remain warm to neutral.

Lastly, the tropical North Atlantic (i.e., TNA) indicates warm to neutral SST anomalies.

The maps on the right (top to bottom) indicate the observed SST for September 2025 and the climatological normal from 1991 to 2020, providing context for the SST anomaly maps.