Inter-monsoon conditions with light and variable winds expected in 1st fortnight of April 2018. Expect afternoon thundery showers which can be intense at times, accompanied by high lightning activity. Some warms days expected.
Singapore, 2 April 2018 – In the first fortnight of April 2018, the low level northeasterly winds are forecast to gradually shift to become light and variable in direction. The change in conditions would signal the cessation of the Northeast Monsoon season and the start of the inter-monsoon period.
2 Inter-monsoon conditions are forecast to prevail in April and extend into May 2018. The period is characterised by warm weather and thunderstorms, at times intense, occurring in the afternoon and evening. During the inter-monsoon months, lightning activity tends to be higher than other months of the year.
3 The first fortnight of April 2018 is not expected to be as wet as the last two weeks of March 2018. In the first half of the month, short-duration thundery showers, which can be heavy at times, are expected in the afternoon and evening on seven to nine days. Overall, the rainfall for the first fortnight of April 2018 is expected to be below average.
4 April is climatologically one of the warmest months of the year. In the first half of April 2018, some warm days with daily maximum temperatures of around 34°C can be expected. On a few days when dry and warm weather conditions are forecast, the daily maximum temperatures could reach a high of around 35°C. The daily minimum temperature is forecast to range between 23°C and 25°C, with the lower temperature on 23°C likely when it rains for most parts of the day.
REVIEW (1 – 31 March 2018)
6 Northeast Monsoon conditions prevailed in the region in March 2018. The low level winds over Singapore blew predominantly from the northeast or northwest.
7 In March 2018, most of the thundery showers occurred in the afternoon due to strong daytime heating of land areas and/or convergence of winds over Singapore or surrounding sea areas. The thundery showers were intense on a few afternoons. In particular, on 30 March 2018, the downdraft from an intense thunderstorm brought heavy rainfall and gusty winds to the western parts of Singapore around Choa Chu Kang and Jurong. The strongest wind gust recorded that day was 133.3 km/h at Tengah which was the strongest wind gust recorded since 2010. While the rainfall from the intense thunderstorm on 30 March 2018 was heavy, it did not record the highest daily rainfall for the month. The highest daily rainfall for March 2018 was 93.2mm recorded at Queenstown due to a heavy downpour in the afternoon of 24 March 2018.
8 The daily maximum and minimum temperature recorded in March 2018 ranged from 26.6°C to 35.7°C, and from 21.4°C to 24.7°C respectively. There were some warm days in March 2018 where the daily maximum temperature recorded on five of these days were in the 35°C range. The high daily maximum temperatures were recorded around the northern and western parts of the island around the Admiralty and Clementi areas.
9 Most parts of Singapore received well below-normal rainfall in March 2018. The lowest rainfall of 38mm (82% below average) was recorded at Paya Lebar. Rainfall was highest around Jurong area where 280.0mm (31% above average) was recorded.
 A monsoon surge refers to the strengthening of northeasterly winds blowing from a strong high-pressure system over the northern Asian continent toward the South China Sea, bringing periods of prolonged widespread rain and windy conditions to the surrounding region including Singapore and Peninsular Malaysia. (Further information is available at www.weather.gov.sg/learn_weather_systems/).
CLIMATE STATION STATISTICS FOR APRIL (Climatological reference period: 1981 – 2010)
|Mean daily maximum temperature||32.3 °C|
|Mean daily minimum temperature||25.0 °C|
|Mean monthly temperature||28.0 °C|
|Mean rainfall for the month||154.8 mm|
|Mean number of rain days||14|
|Highest monthly mean daily maximum temperature||33.9 °C (1983)|
|Lowest monthly mean daily minimum temperature||23.9 °C (1982)|
|Highest monthly rainfall||311.6 mm (2000)|
|Lowest monthly rainfall||43.1 mm (1983)|