A Windy Start to the New Year

WEATHER OUTLOOK (31 December 2019 – 15 January 2020)

Singapore, 31 December 2019 – The prevailing wet phase of the Northeast Monsoon season in the region is forecast to continue into January 2020. The low-level winds during the first two weeks of the year are expected to blow from the northwest or northeast.

2        From the eve of the New Year, the northeasterly winds over the South China Sea, including Singapore are forecast to strengthen and persist before weakening around the end of the week. This is expected to bring windy conditions throughout the week, including on New Year’s Day. Toward the end of the week, periods of light to moderate showers are expected on a few days. In the second week of January 2020, convergence of winds coupled with strong daytime heating of land areas is likely to bring short-duration moderate to heavy thundery showers, mostly in the afternoon on 3 to 4 days. In addition, the presence of a low-pressure system over the South China Sea could bring widespread thundery showers accompanied by gusty winds to Singapore between the predawn and morning on one or two days. Overall, the rainfall for the first two weeks of January 2020 is likely to be below-normal over most parts of Singapore.

3         In the first fortnight of January 2020, the daily temperatures on most days are forecast to range between 24°C and 33°C, and could dip to a low of around 23°C on a few nights. The daily maximum temperature could still reach a high of around 34°C on a few days.

4         For updates of the daily weather and haze situation, please visit the MSS website (www.weather.gov.sg), NEA website (www.nea.gov.sg), or download the myENV app, MSS’ Weather@SG app, and the haze microsite (www.haze.gov.sg).

REVIEW (1 – 30 December 2019)

5        Northeast Monsoon conditions persisted over Singapore in December 2019, with low-level winds blowing mainly from the north or northeast.

6         December 2019 was a relatively wet month. Strong solar heating of land areas coupled with convergence of winds in the surrounding region brought moderate to heavy thundery showers in the afternoon on the first few days of the month. The intense thundery showers on 2 December 2019 recorded a daily total rainfall of 102.8mm at Bukit Panjang. This was the highest daily total rainfall recorded for December 2019 (as of 30 December 2019).

7          A surge of northeast monsoon winds prevailed over the equatorial South China Sea region in the first half of the month. Between 5 and 15 December 2019, the surge brought cloudy and windy conditions to Singapore. During the period from 9 to 11 December 2019, periods of moderate to occasionally heavy rain showers fell over the island, and over the last three days (13 to 15 December 2019) of the fortnight, the rain showers were widespread and fell continuously before dissipating in the evening of 15 December 2019. The highest daily total rainfall recorded throughout this monsoon surge event was 100.4 mm on 9 December 2019 at Pulau Ubin. In the second half of December 2019, the thundery showers were of short-duration and fell mostly in the afternoon. The heaviest rainfall recorded during the period was 63.3 mm at Queenstown on 18 Dec 2019 (as of 30 Dec 2019).

8          The monsoon surge and the accompanying rainy weather in the first half of the month brought several cool days. From 8 to 15 December 2019, the daily maximum temperature ranged between 25.2°C and 29.9°C on all days except 12 December 2019. The lowest daily maximum temperature for December 2019 (as of 30 Dec 2019) was 25.2°C, recorded on 15 December 2019 at Changi. The daily minimum temperature dipped to 23°C and below on seven consecutive days (10 – 16 December 2019) at stations in the northern, central and eastern parts of the island. The lowest daily minimum temperature recorded in December 2019 (as of 30 December) was 21.4 °C, recorded on 2 December 2019 at Admiralty. The lowest–ever recorded daily minimum temperature for December is 20.6°C at Paya Lebar in 1964.

9          At the climate station in Changi, the monthly total rainfall of 421.5 mm for December 2019 (as of 30 Dec 2019) has outranked the December 2017 total rainfall record (371.2mm) as the wettest December in Singapore in the last 10 years. December 2019 was also the windiest December in the last 10 years with an average daily wind speed of 9.8 km/h (as of 30 Dec 2019). The last occurrence when the Changi climate station recorded an average daily wind speed stronger than 9.8 km/hr was in 2009 (at 11.9 km/h).

10        Most parts of the island recorded above-average rainfall in December 2019. The highest anomaly of 51% above average was recorded at Pasir Ris. The anomaly was lowest at Jurong at 18% below average.

CLIMATE STATION STATISTICS

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

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