Rainfall

For AMJ 2025, near to above-normal rainfall is predicted for much of the northern ASEAN region and southeastern Maritime Continent based on the multi-model ensemble (Figure 4). While the UK Met Office and ECMWF models (Figure 3 and 2) show relatively higher confidence of above-normal rainfall over much of the eastern parts of the Maritime Continent, the NCEP model (Figure 1) predict a mix of below- to above-normal rainfall for the region. For Mainland Southeast Asia, the UK Met Office model predict the largest extent of above-normal rainfall, with the NCEP and ECMWF models predicting a mix of near- to above-normal rainfall. Models’ skill is generally moderate to good for above-normal rainfall over the northern ASEAN region and the southeastern Maritime Continent.

Below-normal rainfall is predicted over the western half of the equatorial region, based on the multi-model ensemble (Figure 4). The NCEP model (Figure 1) predicts below-normal rainfall over this region with highest likelihood and largest extent (stretching across the whole region), followed by the ECMWF model (Figure 2) with below-normal rainfall predicted over the western half, while the UK Met Office model (Figure 3) predicts below-normal rainfall only over the western most region. The models’ skill for below-normal rainfall is low to moderate over this region.