Subseasonal Weather Outlook (13 – 26 December 2021)

Issued 10 December 2021
First forecast week: 13 December – 19 December
Second forecast week: 20 December – 26 December


Figure 1: Rainfall Outlook


Figure 2: Temperature Outlook


In Week 1 (13 – 19 December), wetter conditions are expected over central parts of the Philippines and the eastern coastal regions of Mainland Southeast Asia. However, these wetter conditions are highly dependent on the tropical cyclone development. Also in Week 1, wetter conditions are expected over both western and eastern parts of the equatorial region.

Drier conditions are expected over the central equatorial region in Week 2 (20 – 26 December).

Warmer than usual temperature is expected over the southeastern parts of the Maritime Continent in Week 1 (13 – 19 December).

A Madden-Julian Oscillation (MJO) signal propagated eastward from the eastern Maritime Continent (Phase 5) to the Western Pacific (Phases 6 and 7) in the first fortnight of December. However, most models predict this signal to decay in the second week of the forecast period as it propagates eastwards towards Western Hemisphere and Africa (Phase 8).
The outlook is assessed for the region in general, where conditions are relative to the average conditions for the corresponding time of year. For specific updates on the national scale, the relevant ASEAN National Meteorological and Hydrological Services should be consulted.