Mostly Afternoon Thundery Showers for Rest of 2019

WEATHER OUTLOOK (16 – 31 December 2019)

Singapore, 16 December 2019 – Singapore and the surrounding region are currently in the wet phase of the Northeast Monsoon season. This phase is expected to prevail into January 2020 before transitioning to the dry phase of the season (February – mid-March). For the second fortnight of December 2019, the low-level winds are forecast to blow from the northwest or northeast.

2          For the rest of December 2019, strong daytime heating of land areas coupled with localised convergence of winds are expected to influence the weather in Singapore on eight to ten days in the fortnight. These conditions are conducive for localised thunderstorm cloud development, and are forecast to bring moderate to heavy thundery showers in the afternoon. On some of these days, the showers could extend into the evening. Showers are likely around the Christmas period. Overall, the rainfall for December 2019 is expected to be well above average.

3          In the last fortnight of 2019, the daily temperatures are forecast to range between 24°C and 33°C on most days, and could dip to a low of around 23°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 – 15 December 2019)

5          Northeast Monsoon conditions prevailed over Singapore and the surrounding region in the first fortnight of December 2019.  During the period, it was windy with low-level winds blowing from the northeast or east, arising from the monsoon surge that prevailed on most days over the equatorial Southeast Asia region including Singapore.

6          On the first few days of December 2019, strong solar heating of land areas coupled with convergence of winds in the surrounding region brought moderate to heavy thundery showers in the afternoon. 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 the first fortnight of December 2019. A surge of northeast monsoon winds prevailed throughout the fortnight since 5 December 2019, and brought cloudy and windy conditions to Singapore. While there were some passing showers over the island in the first week, periods of moderate to occasionally heavy rain/showers fell on all but one day in the second week of December 2019. Over the 13 December 2019 weekend, the rain was widespread and fell continuously over the island before dissipating in the evening of 15 December 2019. The highest daily total rainfall recorded over this weekend was 80.9mm on 15 December 2019 at Loyang. The highest daily total rainfall recorded throughout this monsoon surge event was 100.4 mm on 9 December 2019 at Pulau Ubin.

7          Compared to the last fortnight of November 2019, the rainy weather in the first fortnight of December 2019 brought cooler temperatures across Singapore. The daily maximum temperature in the first week of the fortnight ranged between 27.3°C and 34.9°C but dipped to between 25.2°C and 32.3°C in the second week of the fortnight due to the rainy weather arising from the monsoon surge. The lowest daily maximum temperature of 25.2°C was recorded on 15 December 2019 at Changi. The lowest daily minimum temperature recorded in the fortnight was 21.4°C on 2 December 2019 at Admiralty, arising from the intense thunderstorm that fell over the island that afternoon.

8          In the first half of December 2019, Singapore recorded above-average rainfall across the island. Pasir Ris recorded the highest rainfall anomaly of 151% while Ulu Pandan recorded the lowest rainfall anomaly of 10% above average.

CLIMATE STATION STATISTICS

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

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