Rainfall
Monthly Rainfall Outlook: August 2025
Issued: 30 Jul 2025
For August 2025, above-normal rainfall is predicted over the southern and eastern Maritime Continent.
For August 2025, above-normal rainfall is predicted over most of the southern and eastern Maritime Continent based on the multi-model ensemble (Figure 1), with most models (more than six models, Figure 2) predicting above-normal rainfall as the dominant tercile for the southern region. A mix of below- to above-normal rainfall is predicted over northwestern Mainland Southeast Asia by some of the models (4 – 6 models in agreement). Elsewhere, no dominant tercile is predicted by the multi-model ensemble. Model skill is good for predicting above-normal rainfall over the southern Maritime Continent, and low to moderate for predicting below- and above-normal rainfall for the other mentioned regions.
Figure 1: Rainfall tercile summary predictions of the multi model ensemble for August 2025 (contains modified Copernicus C3S information).
Figure 2: Number of models in agreement in the multi-model ensemble for the dominant tercile for August 2025. Where there no dominant tercile, it refers to the number of models with near-normal tercile (contains modified Copernicus C3S information).
Figure 5: Average climatological rainfall's lower tercile boundary for August based on CHIRPS (Reference period: 1991-2020).
Figure 6: Average climatological rainfall's upper tercile boundary for August based on CHIRPS (Reference period: 1991-2020).
The qualitative outlook is assessed for the region in general. For specific updates on the national scale, the relevant ASEAN National Meteorological and Hydrological Services should be consulted.