Second Half of May 2018 Expected To Be Wet and Warm

Wetter conditions expected in 2nd half compared to 1st half of May 2018. Expect thundery showers on 6 – 8 days between late morning and afternoon, and a few days between predawn and early morning. Warm temperatures expected on some days.

Singapore, 16 May 2018 – The prevailing inter-monsoon conditions are forecast to persist for the rest of May 2018. During this period, the low level winds are expected to be light and variable in direction.

2          Compared to the first half of May 2018, the second half of May 2018 is forecast to be wetter.  In the next fortnight, moderate to heavy short-duration thundery showers are forecast between the late morning and afternoon on six to eight days. In addition, in the last week of the month, the eastward passage of Sumatra squalls could bring widespread thundery showers accompanied by occasional gusty winds to Singapore between the predawn hours and early morning on two or three days. The rainfall for May 2018 is expected to be near normal.

3          May is climatologically one of the warmest months of the year, and the warm conditions experienced on several days in the first half of May 2018 can still be expected in the second fortnight of the month. On a few afternoons, when there is less cloud cover coupled with strong solar heating of land areas, the daily maximum temperature could reach a high of around 35°C On a few nights, the minimum temperature is forecast to be around 27°C, and warm weather conditions can be expected on these nights. On most days, the daily temperature is expected to range between 25°C and 34°C.

4          For updates of the daily weather forecast, please visit the MSS website (, NEA website (, or download the myENV app, MSS’ Weather@SG app.

REVIEW (1 – 15 May 2018)

5         Inter-monsoon conditions prevailed in the first half of May 2018. The prevailing winds during the period were generally light and variable in direction, and most of the thundery showers fell between the late morning and afternoon. There were a few days when the showers extended into the evening. On 13 May 2018, strong convergence of winds to the east and southeast of Singapore brought thundery showers over many areas between the early hours and mid-day. The showers were heavy over the western part of Singapore between 7am and 11am, and the highest daily total rainfall recorded that day was 121.6mm at Choa Chu Kang.

6         During the first half of May 2018, the daily maximum temperature ranged from 30.8°C to 35.2°C.  There were several warm days experienced in the first fortnight of May 2018. On the 3, 4 and 12 May 2018, the daily maximum temperature recorded in the western, northern and southern parts of Singapore were slightly above 35°C. On a few nights in the second week of May 2018, the daily minimum temperatures recorded over many parts of Singapore were above 27°C. The warm night-time temperatures can be attributed to light winds blowing from the southeast which tend to bring warm and humid air from the sea over the land.

7         About half of Singapore received above-normal rainfall during the first fortnight of May 2018. The lowest rainfall of 23.8 mm (70% below average) was recorded at Changi. Rainfall was highest around Choa Chu Kang where (108% above average) was recorded.




FortnightRain_Anomaly_201805aCLIMATE STATION STATISTICS FOR MAY (Climatological reference period: 1981 – 2010)

Mean daily maximum temperature 32.2 °C
Mean daily minimum temperature 25.4 °C
Mean monthly temperature 28.3 °C
Mean rainfall for the month 171.2 mm
Mean number of rain days 14
Highest monthly mean daily maximum temperature 33.6 °C (1997)
Lowest monthly mean daily minimum temperature 24.5 °C (1981,1982,1984,1989)
Highest monthly rainfall 370.8 mm (1998)
Lowest monthly rainfall 41.6 mm (1997)