Forecast

MONSOON UPDATE

(Updated on 4 Jun 2025)

The Southwest Monsoon season set in during early June 2025 and is expected to persist until late September or early October with the prevailing winds blowing predominantly from the southeast or southwest. During the Southwest Monsoon season, the monsoon rain band is located far north of the Equator and Singapore is climatologically drier compared to other times of the year.

During the season, tropical cyclones in the Western Pacific Ocean and/or the South China Sea can bring heavy rainfall over parts of the northern ASEAN region, mostly over the Philippines and Vietnam. 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 squall lines over Sumatra or the Strait of Malacca (Sumatra squalls). The eastward passage of these squalls towards the South China Sea can bring widespread thundery showers with gusty winds over Singapore between the predawn hours and morning.

In addition to thundery showers from Sumatra squalls, Singapore can expect the development of localised short-duration thundery showers, mostly in the late morning and afternoon, as the land areas heat up.

With prevailing winds blowing warm, humid air from the sea, nights may be warm and humid with the night-time minimum temperatures at around 28°C on some days. Between June and September, the daily maximum temperature in Singapore could reach a high of around 35°C on a few days. On other days, the daily temperature is forecast to range between 25°C and 34°C.

Near average rainfall and above average temperatures over Singapore are predicted for June to August 2025.

The Southwest Monsoon season is associated with the traditional dry season of the southern ASEAN region, during which there may be extended periods of drier weather. This could lead to an increase in burning activities, and the smoke from these fires may sometimes 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.

The long-term rainfall and temperature statistics* for June to September at our Changi climate station are shown in Table 1.

Table 1: Long-term rainfall and temperature statistics for June to September

For the latest weather forecast, including heavy rain warnings, please visit our MSS website (www.weather.gov.sg), NEA website (www.nea.gov.sg) or download the myENV app.

*based on 30-yr climatological reference period (1991-2020)

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