seasonal forecast for June, July, August

Updated 13 June 2017

The Southwest Monsoon onset in early June 2017 and will persist for the next few months. The monsoon season is usually associated with the traditional dry (rainy) season of the southern (northern) ASEAN region, with the prevailing winds blowing from the southeast or southwest. During the season, the presence of tropical cyclones in the Western Pacific Ocean and South China Sea could bring heavy rainfall over parts of the northern ASEAN region, particularly over the Philippines and Vietnam.

For the southern ASEAN region, extended periods of dry weather conditions can be expected. This could lead to an escalation in hotspot activities over the fire-prone provinces of Sumatra and Kalimantan. Typically, in the early part of the traditional dry season in the southern ASEAN region, most of the fires emerge in northern and central Sumatra and western Kalimantan. Vigilance should be stepped up for any escalation of fire activities in the coming dry season.

In the second and third week of June 2017, near-normal to above-normal rainfall is expected for the northern ASEAN region while below-normal to near-normal rainfall is forecast for the southern ASEAN region. Toward the end of June 2017, increased rainfall activities are expected to bring wetter than usual conditions over the southern ASEAN region. For the northern ASEAN region, drier than usual weather conditions are expected.

For the upcoming Northern Hemisphere summer monsoon season (June-July-August), drier than normal conditions are expected over central and southern Southeast Asia, including southern Sumatra, southern Kalimantan, Java, Singapore and Sarawak. There is a slightly enhanced probability of wetter than normal conditions over coastal Myanmar, northern Thailand, northern Philippines, northern Papua, and northern Kalimantan. Near normal conditions are predicted for the rest of the region, including most of mainland Southeast Asia.

Near normal or above normal temperatures are expected over much of Southeast Asia for the Northern Hemisphere summer monsoon season (June-July-August). Above normal temperature is expected over much of Indonesia, Singapore, Brunei, Sarawak, Thailand, and northern Myanmar.

Probabilistic rainfall outlook for the June-July-August 2017 season.

Probabilistic temperature outlook for the June-July-August 2017 season.