Singapore, 17 May 2021 – The prevailing inter-monsoon conditions over Singapore and the surrounding region are expected to persist for the rest of May 2021. During this period, the light and variable low-level winds are forecast to gradually strengthen to blow from the southeast or southwest in the latter half of the fortnight.
2 In the second fortnight of May 2021, short-duration thundery showers are expected over parts of the island in the late morning and early afternoon on some days due to strong daytime heating of land areas. On a few days, convergence of low-level winds over the Strait of Malacca may trigger the development of Sumatra squalls. The eastward passage of the squall toward the South China Sea is expected to bring widespread thundery showers and gusty winds over Singapore between the predawn hours and morning.
3 In the latter half of the fortnight, the monsoon rain band is forecast to shift further north of the Equator, away from Singapore. This is expected to bring less rainfall over the equatorial Southeast Asia region, including Singapore. In addition, with a low pressure system forecast to develop over the northern South China Sea, this could bring drier and warmer conditions over Singapore and the surrounding region. Overall, the rainfall for May 2021 is expected to be below average over some parts of the island.
4 For the rest of May 2021, it is expected to be warm and the daily temperature is forecast to range between 24°C and 34°C on most days. With drier weather in the latter half of the fortnight, warmer conditions can be expected with daytime temperatures around 35°C on some days. The weather during the night can be warm when prevailing winds blow from the southeast or south, bringing warm and humid air from the sea over the land. Night-time temperatures of around 28°C are expected on some nights.
5 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 – 16 May 2021)
6 Inter-monsoon conditions prevailed over Singapore and the surrounding region in the first half of May 2021, and the prevailing winds were generally light and blew from the east or southeast. On some days, the prevailing winds shifted to blow from the southwest.
7 In the first fortnight of May 2021, there were thundery showers mainly in the late morning and afternoon over many parts of the island due to strong daytime heating of land areas. On a few of these days, the thundery showers were intense due to convergence of winds in the surrounding region. There were thundery showers over some parts of the island on a few nights.
8 On 5 May 2021, moderate to heavy thundery showers fell over the northern and central parts of Singapore in the afternoon. The daily total rainfall of 113.6mm recorded at Upper Peirce Reservoir that day was the highest daily total for the first half of May 2021.
9 The warm weather in April 2021 continued into the first half of May 2021. There were 9 days where maximum temperatures of 34°C or more were recorded. The highest daily maximum temperature of 35.7°C was recorded at Marina Barrage on 11 May 2021.
10 Rainfall was near-average for most parts of Singapore in the first half of May 2021. The highest anomaly of 73% above average was recorded at Jurong West. The lowest anomaly of 58% below average was at Kranji.
CLIMATE STATION STATISTICS
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) |