Rainfall
Monthly Rainfall Outlook: April 2026
For April 2026, below-normal rainfall is predicted over most of the southern ASEAN region, while near-normal or no dominant tercile is predicted for the northern ASEAN region.
For April 2026, below-normal rainfall is predicted over most of the southern ASEAN region, based on the multi-model ensemble (Figure 1). For the southernmost part of this region, most of the models (more than six models, Figure 2) predict below-normal rainfall as the dominant tercile, while four to six models agree on below-normal rainfall over much of the equatorial region. Model skill is low to moderate for below-normal rainfall over the southern ASEAN region.
For northern ASEAN region, four to six models agree on the near-normal rainfall predicted over southern Mainland Southeast Asia and southern half of the Philippines, with no dominant tercile being predicted elsewhere (little agreement between the models). Model skill is low to moderate for much of the region.
Figure 1: Rainfall tercile summary predictions of the multi model ensemble for April 2026 (contains modified Copernicus C3S information).
Figure 2: Number of models in agreement in the multi-model ensemble for the dominant tercile for April 2026. Where there is no dominant tercile, it refers to the number of models with near-normal tercile (contains modified Copernicus C3S information).
Figure 3: Average climatological rainfall's lower tercile boundary for April based on CHIRPS (Reference period: 1991-2020).
Figure 4: Average climatological rainfall's upper tercile boundary for April 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.