Warm Weather to Continue in Next Fortnight with Thundery Showers on Most Afternoons

Fortnightly Weather Outlook for 1 – 16 May 2021


Singapore, 30 April 2021 – The warm and wet weather in April 2021 is forecast to continue into the first fortnight of May 2021. With the presence of the monsoon rain band close to the equatorial Southeast Asia region, showers are expected on most days in the first fortnight of May 2021.

2      The prevailing inter-monsoon conditions over Singapore are expected to persist into May 2021. In the first half of May 2021, the low-level winds are forecast to be light and variable in direction and may strengthen to blow from the southwest or west on some days.

3      On most days in the first half of May 2021, short-duration thundery showers with frequent lightning are expected in the afternoon over parts of the island. This is due to strong daytime heating of land areas or coupled with convergence of winds over Singapore and the surrounding vicinity. The showers may extend into the evening on a few days.

4      Also in the first half of May 2021, convergence of low-level winds blowing from the southwest and west may trigger the development of Sumatra squalls over the Strait of Malacca. The eastward passage of the squall toward the South China Sea is expected to bring widespread thundery showers and gusty winds over Singapore on a few days between the predawn hours and morning. Overall, the rainfall in the first half of May 2021 is expected to be above average over most parts of Singapore.

5      Warm conditions are expected on most days in the coming fortnight, and the daily temperature is forecast to range between 24°C and 34°C. The daily maximum temperature could reach around 35°C on a few days, particularly when there are few clouds in the sky. Warm nights can be expected with night-time temperatures of up to 28°C on a few days, mostly over the southern and eastern coastal areas of the island when prevailing winds blowing from the east or southeast bring in warm and humid air from the seas.

6      For updates of the daily weather forecast, please visit our MSS website (www.weather.gov.sg), NEA website (www.nea.gov.sg), or download the myENV app.


REVIEW (1 – 30 April 2021)

7      In April 2021, inter-monsoon conditions prevailed over Singapore and the surrounding region. During the month, the prevailing winds were generally light and variable in direction. Under the influence of a few tropical storms over the Western Pacific Ocean, the prevailing winds strengthened and blew from the southwest or west on some days.

8      On most days in April 2021, thundery showers fell in the afternoon over many parts of the island due to strong daytime heating of land areas. On a few of these days, the showers extended into the evening and night due to large-scale convergence of winds in the surrounding region.

9      On 17 April 2021, the influence of Typhoon Surigae over the Western Pacific Ocean triggered the development of a Sumatra squall over the Strait of Malacca in the morning. The squall brought widespread thundery showers over Singapore between the late morning and afternoon. The rain was heaviest over the western and southern parts of the island with several rainfall stations recording more than 100mm of rain that afternoon. The daily total rainfall of 170.6mm recorded at Ulu Pandan that day was the highest rainfall recorded for April 2021. It is also the record highest rainfall in a day for April since 1980, surpassing the previous record of 159.9mm set in 2007.

10     It was generally warm in April 2021. The daily maximum temperature was above 34°C on most days, with 11 days recording temperatures of 35°C or more. The highest daily maximum temperature of 36.3°C was recorded at Ang Mo Kio on 2 April 2021.

11     Many parts of Singapore recorded well above-average rainfall in April 2021. The rainfall anomaly was highest at Mandai at 110% above average.






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

Average daily maximum temperature 32.2 °C
Average daily minimum temperature 25.4 °C
Average monthly temperature 28.3 °C
Average rainfall 171.2 mm
Average number of rain days 14


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

Highest monthly mean daily maximum temperature: 33.6 °C (1997)
Lowest monthly mean daily minimum temperature: 23.5 °C (1974)
Highest monthly rainfall ever recorded: 386.6 mm (1892)
Lowest monthly rainfall ever recorded: 41.6 mm (1997)