Southwest Monsoon to Bring More Warm and Humid Nights

Southwest Monsoon to bring more warm and humid nights. Short-duration thundery showers forecast on 6 to 8 days in late morning and early afternoon. Widespread thundery showers with gusty winds on 2 to 3 days in predawn hours and morning.

Fortnightly Weather Outlook for 31 May – 13 June 2019


Singapore, 31 May 2019 – In the first fortnight of June 2019, the prevailing light and variable winds over Singapore and the surrounding region are forecast to strengthen and blow from the southeast or southwest. This signals the end of the inter-monsoon period and the start of the Southwest Monsoon season. The Southwest Monsoon season typically extends into September and is a generally drier season compared to other times of the year.

2          The weather in the first fortnight of June 2019 is forecast to be just as wet as it was in the last fortnight of May 2019. With strong day-time heating of land areas, thundery showers are expected mostly in the late morning and early afternoon on six to eight days. On two to three days in the coming fortnight, Sumatra squalls moving from the Strait of Malacca to the South China Sea could track over Singapore and bring widespread thundery showers and occasional gusty winds in the morning. The overall rainfall for the first half of June 2019 is likely to be above-normal over most parts of Singapore.

3          The warm and humid conditions in May 2019 are forecast to persist into the first fortnight of June 2019. With the setting in of the Southwest Monsoon season, more warm and humid nights can be expected; warm nights typically occur when the prevailing winds blow from the southeast and brings warm, humid air from the sea over the land. The daily temperature on most days is forecast to range between 25°C and 33°C. Night-time minimum temperatures of up to 28°C can be expected on some days.

4         For updates of the daily weather forecast, please visit our MSS website (, NEA website (, or download the myENV app, or the MSS’ Weather@SG app.


REVIEW (1 – 30 May 2019)

5          Inter-monsoon conditions prevailed in Singapore and the surrounding region in May 2019. During this period, the low level prevailing winds were generally light and variable in direction, and on occasions, blew from the east or southeast.

6          In May 2019, thundery showers due to convergence of winds over Singapore and the surrounding vicinity, fell in the late morning and afternoon on most days. On several days, particularly in the second week of the month, the passage of Sumatra squalls brought widespread thundery showers to Singapore between the predawn and early morning. The thundery showers were heaviest on 16 May 2019 where the highest daily rainfall total recorded was 119.8mm at Jurong Pier. A waterspout, associated with an intense Sumatra squall, was sighted over the sea area south of Tanjong Pagar on 11 May 2019.

7          May is climatologically one of the warmest months of the year. In May 2019, the highest daily maximum temperature across the island was at least 34°C on more than half the number of days of the month. The highest daily maximum temperature of 35.0°C was recorded at Paya Lebar and Clementi on 6 and 7 May 2019 respectively. The lowest daily minimum temperature of 20.8°C was recorded at East Coast Park around predawn when a squall moved over Singapore on 8 May 2019.

8          At the climate station in Changi, May 2019’s mean monthly temperature of 29.3°C (as of 30 May 2019) is on track to tie with that in May 1997 and 2016 as the second warmest May in Singapore since temperature records started in 1929. In addition, May 2019’s mean daily minimum temperature of 26.5°C is likely to tie the record high set in May 2003 and 2016.

9          Slightly less than half of Singapore received above-average rainfall in May 2019, with most of the rain falling over the southwestern part of Singapore. The highest rainfall of 366.8 mm (78% above average) was recorded at Jurong. Rainfall was lowest over the eastern part of Singapore at Changi where 68.6 mm (56% below average) of rain was recorded.


Long-term Statistics for June
(Climatological reference period: 1981 – 2010)

Average daily maximum temperature 32.0 °C
Average daily minimum temperature 25.4 °C
Average monthly temperature 28.3 °C
Average rainfall 130.7 mm
Average number of rain days 12


Historical Extremes for June
(Rainfall since 1869 and temperature since 1929)

Highest monthly mean daily maximum temperature: 33.2 °C (1997)
Lowest monthly mean daily minimum temperature: 23.2 °C (1965)
Highest monthly rainfall ever recorded: 378.7 mm (1954)
Lowest monthly rainfall ever recorded: 21.8 mm (2009)