Subseasonal Weather Outlook (23 August – 5 September 2021)

Issued 20 August 2021
First forecast week: 23 August – 29 August
Second forecast week: 30 August – 5 September


Figure 1: Rainfall Outlook


Figure 2: Temperature Outlook


Wetter conditions are expected in Week 1 (23 – 29 August) over most of the central and eastern Maritime Continent. These wetter conditions are expected to persist in Week 2 (30 August – 5 September), extending to Java and possibly southern Sumatra.

Elsewhere, wetter conditions are expected in Week 1 (23 – 29 August) over the southern part of Mainland Southeast Asia as well as the coastal parts of Viet Nam. These wetter conditions are generally expected to ease in Week 2 (30 August – 5 September), apart from a small increase in probability that they continue for the coastal regions.

Warmer temperatures are expected over the southern Maritime Continent in the next fortnight (23 August – 5 September). Cooler temperatures than usual are expected in Week 1 (23 – 29 August) over parts of the equatorial region as well as parts of the Philippines.

An MJO signal was present over the Indian Ocean (Phase 2) in the middle of August. Most models predict the MJO to weaken and become indiscernible based on the RMM Index in the forecast 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.