Monthly Archives: April 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 (https://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.

CLIMATE STATION STATISTICS

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

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

Singapore, 1 April 2021 – The Northeast Monsoon conditions that have been prevailing over the region since December 2020 are expected to gradually weaken and end with the onset of inter-monsoon conditions in the first half of April 2021. The prevailing low-level winds over the equatorial Southeast Asia region including Singapore are forecast to become variable in direction and are expected to persist through May 2021.

2      During the inter-monsoon period, warm weather and thundery showers in the afternoon and early evening are common. The prevailing light winds coupled with strong day-time heating of land areas are conducive for the development of localised and intense thunderstorms. During the inter-monsoon months, the incidence of lightning activity is higher than other times of the year.

3      In the first fortnight of April 2021, the monsoon rain band is forecast to lie close to the equatorial Southeast Asia region. Short-duration moderate to heavy thundery showers with frequent lightning are expected over parts of the island in the afternoon on most days. On a few of these days, with strong convergence of winds in the surrounding vicinity, the thundery showers could extend into the early evening.

4      Also in the coming fortnight, the prevailing winds are forecast to shift to blow from the west on a few days. The eastward passage of a Sumatra squall from the Strait of Malacca could bring thundery showers with gusty winds over Singapore on one or two mornings. In addition, on one or two days in the fortnight, it is expected to be fair and warm arising from stable atmospheric conditions over Singapore and the surrounding vicinity. Overall, the rainfall for the first fortnight of April 2021 is expected to be near normal over most parts of the island.

5      Climatologically, April is one of the warmest months of the year. On most days in the first half of April 2021, the daily temperature is forecast to range between 25°C and 34°C. On a few days, the daily maximum temperature could reach a high of around 35°C.

6      For updates of the daily weather forecast, please visit our MSS website (https://www.weather.gov.sg), NEA website (www.nea.gov.sg), or download the myENV app, or the MSS’ Weather@SG app.

REVIEW (1 – 31 March 2021)

7      In March 2021, the dry phase of the Northeast Monsoon prevailed over Singapore and the surrounding region, and the low-level winds blew generally from the north or northeast.

8      Compared to the first fortnight of March 2021 where there were several days of dry and warm conditions, the second fortnight of March 2021 was wet with thundery showers in the afternoon on many days, mostly over the western half of the island. The wet weather was due to strong day-time heating of land areas coupled with convergence of winds either over Singapore or the surrounding vicinity. On 23 March 2021, thundery showers fell over many areas of the island, and was particularly intense over the western half of Singapore. The daily total rainfall recorded that day was 151.5mm at Jurong West. This was the highest daily total rainfall recorded in March 2021.

9      Compared to the second half of March 2021, the first half of the month was generally warmer with more days recording maximum temperatures of 34°C or more. The highest daily maximum temperature of 35.6°C was recorded at Tengah on 2 March 2021. At the Changi climate station, the mean monthly temperature of 27.9°C for March 2021 was 0.4°C higher than the month’s long-term average.

10     Almost all parts of the island recorded average to slightly above average rainfall in March 2021. The highest anomaly of 66% above average was recorded at Ulu Pandan. The anomaly at Ang Mo Kio was 16% below average.

CLIMATE STATION STATISTICS

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

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