Climate Monitoring Node – WMO-RCC-SEA –DOST-PAGASA

Areas of rainfall surplus were observed in most parts of northern to central Philippines, northern Borneo including Brunei Darussalam, eastern Papua, and portions of southern Indonesia. In contrast, several portions of the Southeast Asia (SEA) experienced mild to significant rainfall deficits in January 2026, particularly over northern Peninsular Malaysia and southern Thailand, southern Borneo, Sulawesi, and southern Philippines. The remaining parts of the SEA region experienced near average rainfall conditions.

Over the tropical Pacific, sea surface temperature anomalies (SSTAs) indicate weak La Niña during January 2026, with a weakening trend observed in recent weeks. Sea surface temperatures in the western Pacific and across much of the eastern Maritime Continent were generally near to slightly above average.

In the Indian Ocean, mix of slightly warmer and cooler SST anomalies are observed in the tropical eastern Indian Ocean (i.e., EIO) and the western Indian Ocean (i.e., WIO), reflecting a neutral dipole pattern. In general, there is no prominent tropical Indian Ocean-wide SST anomaly (i.e., IOBW). Lastly, the tropical North Atlantic (i.e., TNA) indicates average to slightly cooler SST anomalies.

Lastly, the Madden–Julian Oscillation (MJO) was observed generally inactive in Week 1 of January, and over the Western Pacific (Phases 6 and 7) for the rest of January 2026. The MJO signal in Phase 6 typically enhances convective activity and increases the likelihood of rainfall over eastern parts of the Southeast Asia (SEA) region, whereas a Phase 7 signal is commonly associated with suppressed rainfall over western portions of SEA.