seasonal forecast for October, November, December

Updated 23 November 2017

The Inter-monsoon conditions over the ASEAN region transited to Northeast Monsoon conditions in the second half of November 2017. The Northeast Monsoon is expected to prevail till March 2018. During the season, the prevailing winds in the region are forecast to blow predominantly from the northeast or northwest.

In the northern ASEAN region, drier weather conditions can be expected with the onset of the traditional dry season towards the end of the year. Hotspot activities are likely to be generally subdued in November 2017 and hotspot activities are expected to gradually increase as the traditional dry season becomes established in late 2017/early 2018.

In contrast, the southern ASEAN region can expect occasional spells of prolonged moderate to heavy rainfall and windy conditions. The increase in rainfall over the next few months is expected to keep hotspot activities in the region generally subdued.

In the last week of November 2017, a monsoon surge is forecast over the South China Sea and surrounding region. The surge could bring a few days of windy conditions and widespread rain mostly to southern Thailand and northern Peninsular Malaysia.

For the upcoming November- December-January season, slightly above-normal to above-normal rainfall is expected for the Philippines. Near-normal rainfall is expected over most parts of the Mekong sub-region, except for Thailand where slightly-below normal rainfall is expected, and Vietnam where slightly above-normal rainfall is forecast for November and December 2017. In the southern ASEAN region, near-normal to slightly above-normal rainfall is expected. For the February-March-April 2018 season, the rainfall over the Philippines is expected to ease to near-normal conditions while increase rainfall conditions can be expected over the Mekong sub-region. Near-normal to slightly above-normal rainfall conditions are expected over parts of Thailand.



  • Legend
  • Above Normal
    (67th to 100th percentile)
  • Slightly Above Normal
    (50th to 83rd percentile)
  • Normal
    (33rd to 67th percentile)
  • Slightly Below Normal
    (17th to 50rd percentile)
  • Below Normal
    (0 to 33rd percentile)