- Monsoon Update
(Updated on 30 November 2018)
Singapore and the surrounding region are currently experiencing the Northeast Monsoon which set in around the end of November 2018. The Northeast Monsoon is expected to prevail till March 2019. During the season, the prevailing low level winds typically blow mainly from the northeast or northwest. The Northeast Monsoon season typically comprise a wet phase from December to January, followed by a dry phase from February to March.
The overall northeast winds for Singapore and the surrounding vicinity in December 2018 are expected to be weaker than normal. This makes it more favourable for the development of afternoon thundery showers, and an above-normal rainfall is forecast over Singapore and the nearby Equatorial region.
A monsoon surge is likely to affect Singapore and the Equatorial South China Sea region in the second week of December 2018; this surge could bring a few days of cooler temperatures, occasionally windy conditions and widespread moderate to heavy rain to the southern Southeast Asian countries. The daily maximum temperature over Singapore could reach to around 29°C and the daily minimum temperature could drop to around 22°C during the period of the surge.
The second half of December is expected to be wetter than the first fortnight of December, and wetter-than-usual conditions can be expected over Singapore and the surrounding vicinity in December 2018.
For the Dec-Jan-Feb 2018/2019 season, near to slightly below-normal rainfall is favoured over Singapore and the surrounding Equatorial Southeast Asia region.
Above-normal temperatures are favoured over much of the Southeast Asia region, including Singapore for this Northeast Monsoon season.
On most days during the wet phase of Northeast Monsoon season, short-duration moderate to heavy thundery showers, mostly in the afternoon. On some of these days, the showers could extend into the evening due to a confluence of winds over Singapore and the surrounding vicinity can be expected. In addition, there can be two to four episodes of monsoon surges which usually bring prolonged, widespread rainfall lasting between two and five days, occasionally windy conditions, and cooler temperatures to Singapore and the surrounding region. The prevailing wet phase of the Northeast Monsoon season is expected to peak in January 2019 before the onset of the dry phase of the Northeast Monsoon season in February 2019.
Based on long-term statistics* at our climate station, with the presence of the monsoon rain band over the equatorial belt, December is normally the wettest month of the year. In February, the monsoon rain belt typically lies south of the Equator and February is generally the driest month of the year. While February may be drier compared to December and January, showers can still be expected over parts of Singapore on some days due to solar heating of land areas. The number of rain days in February is typically less compared to the wet phase of the Northeast Monsoon season.
The long-term rainfall and temperature statistics for December to March at our climate station are shown in Table 1.
For the latest weather forecast, including heavy rain warnings, please visit our MSS website (www.weather.gov.sg), NEA website (www.nea.gov.sg), download the myENV app., Weather@SG app, weather information hotline at 65427788, through following NEA’s twitter via @NEAsg or from radio broadcasts.
*based on 30-yr climatological reference period (1981- 2010)
 A monsoon surge refers to the strengthening of northeasterly winds blowing from a strong high-pressure system over the northern Asian continent toward the South China Sea, bringing periods of prolonged widespread rain and windy conditions to the surrounding region including Singapore and Peninsular Malaysia. This cold surge strengthens the northeasterly winds near the surface and the regional topography acts to restrict the flow as it is channelled towards the equator. Although the surge from the north is relatively cooler and drier, it becomes moister as it travels over the warmer parts of the southern South China Sea and it plays an important role in the episodes of enhanced deep convection over the equatorial South China Sea. (Further information is available at www.weather.gov.sg/learn_weather_systems/).