Subseasonal Weather Outlook (21 September – 4 October 2020)

Issued 21 September 2020
First forecast week: 21 September – 27 September
Second forecast week: 28 September – 4 October


Figure 1: Rainfall Outlook


Figure 2: Temperature Outlook

Wetter conditions are predicted over the equatorial region in the first week (21 – 27 September), easing in most places except Papua in the second week (28 September – 4 October).

Warmer conditions are expected during the fortnight over most of Mainland Southeast Asia (except northern Myanmar), the Philippines and southern parts of Southeast Asia, with closer to normal temperatures in the equatorial region (corresponding to the wetter conditions in the rainfall outlook).

The previous Madden-Julian Oscillation (MJO) signal weakened after entering the Maritime Continent (Phase 4), just before the start of the forecast period. Most models predict this weak MJO signal to continue propagating across the Maritime Continent and over the Western Pacific.
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.