seasonal forecast for December, January, February

Updated 8 December 2017

The current Northeast Monsoon season is expected to extend into March 2018, with prevailing winds in the region blowing predominantly from the northwest or northeast. The Northeast Monsoon will generally bring drier and cooler conditions to the northern ASEAN region. Hotspot activities are expected to gradually increase in the Mekong sub-region as the traditional dry season becomes established in January 2018.

In the southern ASEAN region, shower activities coupled with occasional periods of prolonged moderate to heavy rain can be expected in the coming season. Hotspot activities are likely to be subdued by the expected wet weather conditions.

In the second week of December 2017, below-normal rainfall is expected for most parts of the Mekong sub-region. A monsoon surge can be expected over the South China Sea and the surrounding region, and could bring a few days of cooler temperatures, occasionally windy conditions and widespread moderate to heavy rain to the southern Southeast Asian countries. Above-normal rainfall is forecast for the northern parts of Borneo, central and southern Philippines. In the third week of December, drier than usual conditions will prevail for most parts of the equatorial region, including Sumatra and Borneo. Near-normal to above-normal rainfall is expected for the northern ASEAN region. In the last week of December, near-normal rainfall is expected for the western parts of the Maritime Continent. Above-normal rainfall is forecast for the Philippines and rainfall is likely to be below-normal for the eastern parts of southern ASEAN region.

For the upcoming boreal winter (Dec-Jan-Feb 2017/2018) season, above-normal rainfall is favoured over the eastern Maritime Continent, southern Vietnam, and central and southern Thailand. Below-normal rainfall is slightly favoured over western Borneo and northern Southeast Asia. Elsewhere near-normal rainfall is favoured.

Above-normal temperatures are favoured over much of the Southeast Asia region for the upcoming boreal winter monsoon season, with higher probabilities over the eastern Maritime Continent, northern Southeast Asia, and Sumatra. Below-normal temperatures are favoured over northern Philippines and southern Vietnam.