Fortnightly Weather Outlook for 15 – 31 January 2021
Singapore, 15 January 2021 – The prevailing Northeast Monsoon season is forecast to continue for the rest of January 2021 with low-level winds blowing from the northwest or northeast. Compared to the exceptionally wet and cool first fortnight of the year, the second fortnight of January 2021 is forecast to be generally dry and warm. Daily maximum temperatures in the coming fortnight are expected to range between 32°C and 33°C on most days, with highs of around 34°C on a few days.
2 In the second fortnight of January 2021, short-duration thundery showers due to strong day time heating of land areas can be expected mostly in the afternoon over parts of the island on some days. In addition, with stable atmospheric conditions arising from the presence of a dry air mass over the equatorial Southeast Asia region, Singapore can expect fair and occasionally windy conditions on a few days. While rainfall for the second half of January 2021 is expected to be below normal, the overall rainfall for January 2021 is forecast to be well above-normal due to the exceptionally wet weather in the first half of the month.
3 On most days in the second half of January 2021, the daily temperatures are forecast to range between 24°C and 33°C. It is expected to be warm with daily maximum temperatures of around 34°C on days with little or no rain and when winds are light.
REVIEW (1 – 14 January 2021)
5 In the first fortnight of January 2021, Northeast Monsoon conditions prevailed over Singapore and the surrounding region. During the fortnight, the low-level winds blew mostly from the northeast.
6 The first half of January 2021 was exceptionally wet and cool due to a surge of northeast monsoon winds (monsoon surge1) over the equatorial South China Sea region on 1-2 January 2021 and again on 8 – 13 January 2021. The New Year weekend surge event brought widespread continuous rain, heavy at times over the island. The highest daily total rainfall recorded on 1 and 2 January 2021 were 147.3mm at Upper Changi Road East and 210.6mm at the Changi climate station respectively. The total rainfall at the climate station on 2 January 2021 was slightly less than the record high in a day for January at 216.2mm (on 30 January 2011).
7 The second monsoon surge event started on 8 January 2021 and persisted over the equatorial South China Sea for the next few days before it eased on 13 January 2021. The surge coupled with large-scale convergence of winds over Singapore and the surrounding vicinity brought windy and rainy weather during the period. It was particularly windy with continuous rain, heavy at times over the island on 10 January 2021. The highest daily total rainfall of 204.0mm recorded during the 6-day surge event was on 10 January 2021 at Changi.
8 At the Changi climate station, the total rainfall in the first two weeks of January 2021 was 648.4mm which ranks January 2020 as the wettest January in the last 30 years. This surpasses the 600.9mm recorded in January 2004. Based on long term statistics, January 2021’s total rainfall (to date) of 648.4mm also ranks January 2021 as the second wettest January since rainfall records in Singapore began in 1869. The wettest ever January in Singapore on record is January 1893 with a monthly total of 818.6mm.
9 The first fortnight of January 2021 was also exceptionally cool due to the cloudy and rainy weather arising from the two monsoon surge events. The daily maximum temperature was below 30°C on all days in the fortnight except for 5, 6 and 14 January 2021. The daily minimum temperature dipped to 23°C and below on the first five days of the year. The lowest daily minimum temperature in the first fortnight of the month was 21.1°C, recorded on 2 January 2021 at Newton.
10 It was also relatively windy in the first half of January 2021. At the Changi climate station, wind gusts of up to 46.9km/h were recorded on 12 Jan 2021 during the second monsoon surge event. The highest ever recorded wind gust for January at the Changi climate station was 73.4km/h. Island-wide, the highest maximum wind gust recorded in the first half of January 2021 was 70.2km/h at Admiralty on 12 January 2021.
11 Singapore received significantly above normal rainfall in the first fortnight of January 2021. The highest anomaly of 511% above average was recorded at Changi. The anomaly was lowest at Jurong at 153% above average.
1 A monsoon surge refers to a strengthening of winds over the South China Sea, causing extensive rainclouds to form over our surrounding region.
CLIMATE STATION STATISTICS
Long-term Statistics for January
(Climatological reference period: 1981 – 2010)
|Average daily maximum temperature||30.4 °C|
|Average daily minimum temperature||23.9 °C|
|Average monthly temperature||26.5 °C|
|Average rainfall||234.6 mm|
|Average number of rain days||13|
Historical Extremes for January
(Rainfall since 1869 and temperature since 1929)
|Highest monthly mean daily maximum temperature:||31.8 °C (1998, 2016)|
|Lowest monthly mean daily minimum temperature:||21.6 °C (1934)|
|Highest monthly rainfall ever recorded:||818.6 mm (1893)|
|Lowest monthly rainfall ever recorded:||15.4 mm (1997)|