Rainfall
Monthly Rainfall Outlook: January 2026
Issued: 30 Dec 2025
For January 2026, above-normal rainfall is predicted for much of the northeastern and southern Maritime Continent.
For January 2026, above-normal rainfall is predicted over much of the northeastern and southern Maritime Continent based on the multi-model ensemble (Figure 1). Below-normal rainfall is predicted over parts of the central Maritime Continent. For both regions, there is (more than six models, Figure 2) predict above-normal rainfall as the dominant tercile for the northeastern regions and below-normal rainfall as the dominant tercile over central Borneo.
For Mainland Southeast Asia, below-normal rainfall is predicted over the northwestern portion (Figure 1) by most models (more than six models, Figure 2). Elsewhere in Mainland Southeast Asia there is little agreement between the models.
Model skill is good for predicting above-normal rainfall over the northeastern Maritime Continent. Model skill is low to moderate for the other regions mentioned.
Figure 1: Rainfall tercile summary predictions of the multi model ensemble for January 2026 (contains modified Copernicus C3S information).
Figure 2: Number of models in agreement in the multi-model ensemble for the dominant tercile for January 2026. Where there is 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 January based on CHIRPS (Reference period: 1991-2020).
Figure 6: Average climatological rainfall's upper tercile boundary for January 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.