seasonal forecast for July, August, September

Updated 12 July 2017

The prevailing Southwest Monsoon conditions are expected to strengthen over the next few months. The monsoon is associated with the traditional wet (dry) season of the northern (southern) ASEAN region. During the season, prevailing winds are expected to blow from the southeast or southwest. The development of tropical cyclones in the Western Pacific Ocean and South China Sea can be expected and could bring heavy rainfall over parts of the northern ASEAN region, particularly over the Philippines and Vietnam.

For the southern ASEAN region, the dry weather conditions could lead to an escalation in hotspot activities over the fire-prone provinces of Sumatra and Kalimantan. Vigilance should be stepped up for any escalation of fire activities in the coming dry season.

In the second week of July 2017, well above-normal rainfall conditions are expected over many parts of the ASEAN region. For the third week of July, the situation is expected to continue over the northern ASEAN region and South China Sea, although drier than usual conditions are forecast over Sumatra, Peninsular Malaysia and parts of Kalimantan. By the last week of July, below-normal rainfall is expected over Kalimantan while slightly above-normal rainfall is forecast for the Mekong sub-region and the Philippines.

For the upcoming July-August-September season, near-normal rainfall is expected for most parts of the northern ASEAN region, except in northern and central Thailand where slightly above-normal rainfall is expected in July and September. In most parts of the southern ASEAN region, near-normal rainfall is forecast to prevail. However, slightly below-normal rainfall is expected over Singapore, southern Sumatra and Java.