Rainy weather has been forecast for the first half of the month, the Meteorological Service Singapore said in a media advisory yesterday.
Low-level winds are expected to blow mainly from the north-east or north-west.
Moderate to heavy thundery showers are forecast in the afternoon on six to eight days, with the showers extending into the early evening on a few of these days.
A monsoon surge is also expected to bring a few days of occasionally windy conditions, with widespread moderate to heavy rain and cooler temperatures, to Singapore.
Rainfall for the first half of the month is expected to be above normal.
Night-time minimum temperatures are also forecast to be slightly lower, at 23 deg C to 24 deg C, while maximum day-time temperatures are likely to range between 31 deg C and 33 deg C.
In an update on last month's weather, the Met Service said the daily maximum temperature of 33.5 deg C recorded on Dec 1, 2017 was the second-highest daily maximum temperature on record for December - 1 deg C lower than the highest set on Dec 12, 2010.
In addition, the average monthly temperature of 27.1 deg C for last month was 0.7 deg C above the long-term mean for December.
About half of Singapore received above-normal rainfall in December.