Subseasonal Weather Outlook (18 – 31 October 2021)

Issued 15 October 2021
First forecast week: 18 October – 24 October
Second forecast week: 25 October – 31 October


Figure 1: Rainfall Outlook


Figure 2: Temperature Outlook


Over most of the Maritime Continent, wetter conditions are predicted in the next fortnight (18 – 31 October). The highest likelihood for wetter conditions is for the equatorial region in Week 1 (18 – 24 October), while the highest likelihood is over central and eastern parts of the Maritime Continent in Week 2 (25 – 31 October).

Over Mainland Southeast Asia in Week 1 (18 – 24 October), wetter conditions are predicted apart from over western Mainland Southeast Asia. In Week 2 (25 – 31 October), these wetter conditions are generally expected to ease, although a small increase in wetter conditions remains over southern Mainland Southeast Asia.

No significant regional temperature anomalies are expected in the next fortnight (18 – 31 October).

A Madden-Julian Oscillation (MJO) signal propagated eastward from the Maritime Continent (Phases 4 and 5) towards the Western Pacific (Phase 6) in the first two weeks of October. However, most models predict this signal to decay, with no significant MJO activity during the outlook period.
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.