Rainfall

For May 2025, above-normal rainfall is predicted for much of the eastern Maritime Continent based on the multi-model ensemble (Figure 4). The ECMWF and UK Met Office models (Figures 2 and 3, respectively) predicted an increased chance of above-normal rainfall over much of the region, with the highest probability over the southeastern Maritime Continent. The NCEP model (Figure 1), predicts a mix of below- to above-normal rainfall. Elsewhere in the Maritime Continent, the NCEP model predicts predominantly an increase chance of below-normal rainfall, while the ECMWF and UK Met Office models predict near-normal rainfall or no dominant tercile. The model skill for above-and below-normal rainfall is good over the Philippines and moderate to good elsewhere in the region, while the skill for near-normal rainfall is low to moderate for the Maritime Continent.  

For Mainland Southeast Asia, a mix of near-normal and above-normal rainfall is predicted for much of the region, based on the multi-model ensemble (Figure 4). The UK Met Office model (Figure 3) predicts an increased chance of above-normal rainfall for most of Mainland Southeast Asia, while the NCEP and ECMWF models (Figures 1 and 2, respectively), predict a mix of near- and above-normal rainfall or no domain tercile. The models’ skill is moderate to good for above-normal rainfall and low to moderate for near-normal rainfall for Mainland Southeast Asia at this time of the year.