Inter-monsoon Conditions Expected in The Second Half of October 2017

Dry and warm weather expected on a few days

Singapore, 16 October 2017 – The prevailing Southwest Monsoon conditions are forecast to weaken and give way to Inter-monsoon conditions in the second half of October 2017. During the second fortnight of October 2017, the low level winds are forecast to be light and variable in direction, characteristic of the inter-monsoon season which is expected to extend into November 2017.

2          Compared to the first half of October 2017 where thundery showers fell over the island on most days, the second half of October 2017 can expect a mix of dry and wet weather conditions. In the third week of October 2017, a few dry and warm weather days can be expected, and for the rest of the second fortnight, short-duration thundery showers are forecast to fall mostly in the afternoon on four to six days. On a few of these days, the thundery showers could extend into the evening. In addition, on one or two days, the eastward passage of Sumatra squalls could bring widespread thundery showers accompanied by gusty winds over Singapore between the predawn hours and early morning. Overall, the rainfall for October 2017 is expected to be slightly above normal.

3          The daily temperature on most days in the second fortnight of October 2017 is forecast to range between 24°C and 33°C. On a few days when the weather is expected to be dry and warm, or when there is strong solar heating coupled with winds that are light, the daily maximum temperature could lie between 34°C and 35°C.

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

Review: 1 – 15 October 2017

5          In the first fortnight of October 2017, Southwest Monsoon conditions prevailed over Singapore and the surrounding region, and the low level winds were blowing mostly from the southeast or southwest.

6          During the review period, Singapore experienced thundery showers mostly in the afternoon and evening due to strong solar heating of land areas coupled with convergence of winds over Singapore and the immediate surrounding vicinity. On a few days, the eastward passage of Sumatra squalls brought widespread thundery showers and gusty winds to Singapore between midnight and the early morning. In the first fortnight of October 2017, the highest daily rainfall of 129.8mm was recorded around Tuas on 12 October 2017.

7          Despite the wet weather conditions that fell over the island on most days in the first fortnight of the month, there were a few warm days where the highest temperature recorded was 35°C around the Ang Mo Kio area on 15 October 2017. The lowest daily minimum temperature recorded ranged between 22.6°C and 22.9°C.

8           In the first half of October 2017, most parts of Singapore received above-normal rainfall. The highest rainfall of 216.0mm (116% above average) was recorded around the Tai Seng area. Rainfall was lowest around Sentosa where 39.0mm (53% below average) was recorded.FortnightRain_Anomaly_201710a


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

Mean daily maximum temperature 31.7 °C
Mean daily minimum temperature 24.7 °C
Mean monthly temperature 27.6 °C
Mean rainfall for the month 154.6 mm
Mean number of rain days 15
Highest monthly mean daily maximum temperature 33.0 °C (2002)
Lowest monthly mean daily minimum temperature 23.8 °C (1982)
Highest monthly rainfall 351.4 mm (2003)
Lowest monthly rainfall 10.8 mm (2002)