Monthly Archives: April 2018

Inter-monsoon conditions have set in over Singapore.  Expect more short-duration moderate to heavy thundery showers in second half of April 2018 accompanied with high lightning activity.  A few warm days with maiximum temperature around 35 deg C expected. 

Singapore, 16 April 2018 – Inter-monsoon conditions have set in over Singapore and the surrounding region, and are forecast to persist for the rest of April and extend into May 2018. During this period, the low level winds are generally light and variable in direction.

2          The inter-monsoon period is characterised by warm weather and moderate to heavy thundery showers falling mostly in the afternoon and occasionally extending into the evening. Typically, thunderstorms during the inter-monsoon period are more intense than other times of the year. This is due to strong solar heating of land areas as the sun is closer to the Equator. April is climatologically the month with one of the highest number of lightning occurrences.

3          The second fortnight of April 2018 is forecast to be wetter than the first fortnight, with short-duration moderate to heavy thundery showers expected mainly in the afternoon on seven to nine days. Also in this fortnight, Sumatra squalls moving from the Strait of Malacca to the South China Sea could bring widespread thundery showers accompanied with gusty winds over Singapore on two or three days between the predawn hours and early morning. With the expected wetter conditions in the coming fortnight, the overall rainfall for April 2018 is likely to be near average.

4          Climatologically, April is one of the warmest months of the year. In the second half of April 2018, a few warm days can be expected. On most days, the daily temperatures are expected to range between 24°C and 34°C, and could reach a high of around 35°C on a few days. With expected widespread rain on a few days in the coming fortnight, the minimum temperature on these days could reach a low of around 23°C.

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

REVIEW (1 – 15 April 2018)

6          The Northeast Monsoon conditions gave way to the inter-monsoon conditions in the first half of April 2018. The prevailing low level winds over Singapore became light and variable in direction having been predominantly blowing from the northeast or northwest for the past few months.

7          In the first half of April 2018, the strong daytime heating of the land area coupled with generally light winds during the day were conducive conditions for the development of thundery showers over Singapore. Most of the thundery showers fell in the afternoon and were more intense in the second week of April 2018. Rainfall was heaviest on 7 April 2018 around the MacRitchie Reservoir area where the daily total rainfall recorded was 138mm.

8          There were some warm days during the first fortnight of April 2018. The daily maximum temperature ranged between 33.2°C and 34.9°C, particularly over the northern and western parts of Singapore. The highest value of 34.9°C was recorded at Khatib in Yishun. The daily minimum temperature ranged from 22.5°C to 25.5°C.

9         About two-thirds of Singapore received below-normal rainfall in the first fortnight of April 2018. The lowest rainfall of 20.4mm (73% below average) was recorded at Changi. Rainfall was highest around Jurong where 219.8mm (66% above average) was recorded.

CLIMATE STATION STATISTICS FOR APRIL (Climatological reference period: 1981 – 2010)

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.

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

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.

[1] 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  https://www.weather.gov.sg/learn_weather_systems/).

CLIMATE STATION STATISTICS FOR APRIL (Climatological reference period: 1981 – 2010)