- Monsoon Update
(Updated on 5 June 2021)
With the cessation of Inter-monsoon conditions in end May 2021, the prevailing Southwest Monsoon conditions over the region are forecast to persist into late September/early October 2021. During the Southwest Monsoon season, the prevailing winds are expected to blow from the southeast or southwest, and the monsoon rain band is forecast to lie further north, away from the Equator. Climatologically, the Southwest Monsoon season in Singapore is a drier season compared to other times of the year.
Tropical cyclones in the Western Pacific Ocean and/or the South China Sea are common during the Southwest Monsoon season. They can bring heavy rainfall over parts of the northern ASEAN region, mostly over the Philippines and Vietnam, and the rain bands from these tropical cyclones can have an indirect influence on the weather over the equatorial Southeast Asia region, including Singapore.
The presence of these tropical cyclones can at times induce the development of Sumatra squalls which are lines of thunderstorms that develop during the night over Sumatra or the Strait of Malacca. As the squall moves east towards the South China Sea, it can bring widespread thundery showers with gusty winds over Singapore typically between the predawn hours and morning.
In addition to thundery showers from Sumatra squalls in the coming months, localised short-duration thundery showers due to strong daytime heating of land areas, can be expect over Singapore mostly in the late morning and afternoon.
Over Singapore and the equatorial Southeast Asia region, the overall rainfall for June to August 2021 is expected to be normal to above-normal while the overall temperature has been predicted to be above-normal for the same period.
During the season, it is common for the nights to be warm, especially when winds are from the southeast or south. Night-time minimum temperatures can remain around 28°C throughout the night. This is due to warm, humid air being blown in from the sea over the land. Between June and August, the daily maximum temperature in Singapore could reach a high of around 35°C. On other days, the daily temperature is forecast to range between 25°C and 34°C.
Typically, during the Southwest Monsoon months, Singapore can occasionally experience slightly hazy conditions on some days, particularly in the early morning. This is due to the accumulation of particulate matter in the atmosphere when winds are light. This slight haziness usually clears in the later part of the morning when there is mixing of the air with slight strengthening of the winds.
The Southwest Monsoon season is associated with the traditional dry season of the southern ASEAN region, and extended periods of drier weather can be expected during this season. This could contribute to an increase in burning activities in the region. On occasions, the smoke haze emanating from these fires can be carried over to Singapore by the prevailing winds. The impact of the smoke haze is dependent on factors such as the proximity and extent of the fires, the strength and direction of the prevailing winds and the incidence and amount of rain.
Based on long-term climatological records, the rainfall and temperature statistics* for June, July and August at our Changi climate station are shown in Table 1.
|Average Monthly Rainfall Total (mm)||135.3||146.6||146.9|
|Average number of rain days (Days with 0.2mm or more of rainfall)||13||14||14|
|Average Daily Maximum Temperature (°C)||31.9||31.4||31.4|
|Average Daily Minimum Temperature (°C)||25.7||25.4||25.3|
Table 1: Long-term rainfall and temperature statistics for June, July and August.
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 information hotline at 65427788 or through following NEA’s twitter via @NEAsg.
*based on 30-yr climatological reference period (1991-2020)