Category Archives: Fortnightly Weather Outlook

Drier than usual conditions are predicted over much of the southern and eastern Maritime Continent in the next fortnight (26 October – 8 November).

Warmer than usual conditions are predicted over most of the ASEAN region in the next fortnight (26 October – 8 November).

In the middle of October, a Madden-Julian Oscillation (MJO) signal was present over the Western Hemisphere and Africa (Phase 1) based on the RMM Index. There is considerable uncertainty in the MJO outlook during the forecast period. While most models predict an MJO-like signal to develop over the Indian Ocean (Phases 2 and 3) in Week 1 (26 October – 1 November), this is similar to the forecast by some models from two weeks ago that did not transpire.

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.

Drier than usual conditions are predicted over most of the southern ASEAN region in the next fortnight (12 – 25 October). Drier than usual conditions are also predicted for much of northern Mainland Southeast Asia in Week 1 (12 – 18 October).

Warmer than usual conditions are predicted over most of the ASEAN region in the next fortnight (12 – 25 October).

While an active signal was present over the Western Hemisphere (Phases 8 and 1) in the first week of October based on the RMM index, its westward propagation was not characteristic of the Madden-Julian Oscillation (MJO). Most models predict no significant MJO activity by the start of the forecast period. During the forecast period (12 – 25 October), some models predict an MJO to emerge over the Indian Ocean (Phases 2 and 3) in Week 1 (12 – 18 October), while others suggest no significant MJO activity.

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.

Drier than usual conditions are predicted over most of the southern ASEAN region in the next fortnight (28 September – 11 October). Drier than usual conditions are also predicted for parts of the northeastern Maritime Continent and southern Mainland Southeast Asia in Week 1 (28 September – 4 October).

Warmer than usual conditions are predicted over most of the ASEAN region in Week 1 (28 September – 4 October). These warmer conditions are predicted to persist over most of the southern ASEAN region in Week 2 (5 – 11 October).

A Madden-Julian Oscillation (MJO) signal was present over the Western Hemisphere (Phases 8 and 1) in the third week of September, based on the RMM index. Models predict the signal to weaken and become inactive by the start of the forecast period. During the forecast period (28 September – 11 October), most models predict no significant MJO activity.

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.

Drier than usual conditions are predicted over most of the southern ASEAN region in the next fortnight (14 – 27 September).

Wetter than usual conditions are predicted over parts of southern Mainland Southeast Asia and parts of the northwestern Maritime Continent in Week 1 (14 – 20 September).

Warmer than usual conditions are predicted over most of the ASEAN region in the next fortnight (14 – 27 September).

Most models predict no significant MJO activity during the forecast period (14 – 27 September).

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.

Over much of the northern ASEAN region, wetter conditions are predicted in Week 1 (17 – 23 August), except over parts of southeastern Mainland Southeast Asia where drier conditions are predicted over the next fortnight (17 – 30 August).

Over much of the southern ASEAN region, drier conditions are predicted in the next fortnight (17 – 30 August).

Warmer than usual temperatures are predicted over much of the ASEAN region in the next fortnight (17 – 30 August), except for most of Mainland Southeast Asia and the southern Maritime Continent.

A Madden-Julian Oscillation (MJO) signal was present over the Western Pacific (Phase 6) towards the middle of August 2026, based on the RMM index. Models predict the MJO signal to remain over the Western Pacific (Phases 6 and 7) during the forecast period (17 – 30 August), with no coherent sign of eastward propagation.

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.

Over much of the northern ASEAN region, wetter conditions are predicted in the next fortnight (3 – 16 August). The highest likelihood of wetter conditions is over the northwestern parts in Week 1 (3 – 9 August), and over the southern and eastern parts in Week 2 (10 – 16 August).

Over much of the southern ASEAN region, drier conditions are predicted in the next fortnight (3 – 16 August).

Warmer than usual temperatures are predicted over much of the ASEAN region in the next fortnight (3 – 16 August), except for most of Mainland Southeast Asia and the southern Maritime Continent.

A weakening Madden-Julian Oscillation (MJO) signal was present over the Western Hemisphere (Phase 8) in late July 2026, based on the RMM index. Most models predict an MJO signal to develop over the Western Pacific (Phase 6) during Week 1 (3 – 9 August), although models disagree whether the signal will continue to propagate or weaken during Week 2 (10 – 16 August).

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.

Drier conditions are predicted over the equatorial region and parts of the southwestern Maritime Continent in the next fortnight (20 July – 2 August).

Warmer than usual temperatures are predicted over much of the western and central Maritime Continent as well as over most of southern Mainland Southeast Asia and parts of northeastern Maritime Continent in the next fortnight (20 July – 2 August).

A Madden-Julian Oscillation (MJO) signal was present over the Western Pacific (Phase 7) in the first half of July 2026, based on the RMM index. Most models predict the MJO signal to be over the Western Pacific (Phase 7) or the Western Hemisphere (Phase 8) at the start of Week 1 (20 – 26 July) and then weaken and become indiscernible by the start of Week 2 (27 July – 2 August).

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.

Wetter conditions are predicted over much of the northern half of Mainland Southeast Asia in Week 1 (6 – 12 July).

Drier conditions are predicted over much of the southern ASEAN region in the next fortnight (6 – 19 July). The highest chance of drier conditions is over the central and eastern equatorial region.

Warmer than usual temperatures are predicted over much of the Maritime Continent in the next fortnight (6 – 19 July). Warmer than usual temperatures are also predicted over most of central and southeastern Mainland Southeast Asia in Week 2 (13 – 19 July).

There were signs of a Madden-Julian Oscillation (MJO) signal developing towards the end of June 2026. Most models predict the MJO signal to propagate through the Western Pacific (Phase 6 to Phase 7) during Week 1 (6 – 12 July) and then weaken in Week 2 (13 – 19 July).

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.

Drier conditions are predicted over most of the equatorial region in the next fortnight (22 June – 5 July). The highest chance of drier conditions is over the central and eastern equatorial region in Week 1 (22 – 28 June), and over the eastern equatorial region in Week 2 (29 June – 5 July).

Wetter conditions are predicted over parts of the northeastern Maritime Continent and much of central and eastern Mainland Southeast Asia in Week 2 (29 June – 5 July).

Warmer than usual temperatures are predicted over most of the Maritime Continent in the next fortnight (22 June – 5 July). Warmer than usual temperatures are also predicted over most of central and eastern Mainland Southeast Asia in Week 1 (22 – 28 June).

A Madden-Julian Oscillation (MJO) signal was present over the Western Hemisphere and Africa (Phase 1) in the middle of June 2026, based on the RMM Index. Most models predict the MJO signal to decay and become indiscernible by the start of the forecast period. Most of these models also predict an emergence of an MJO signal over the Maritime Continent (Phase 5) or the Western Pacific (Phase 6) during the forecast period (22 June – 5 July), with uncertainty in the timing.

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.