The mercury dropped on Monday to unexpected levels, with a reading of 21.4 deg C in the northern part of Singapore even as thundery showers fell across the island.
This was outside the forecast range by the National Environment Agency's Meteorological Service Singapore (MSS) last Friday, which tipped temperatures to range from 22 deg C to 30 deg C in the first two weeks of this month.
The weatherman told The Straits Times yesterday that the lowest temperature recorded on Monday was 21.4 deg C at 6pm in Admiralty, although this was still higher than the year's low so far - 20.8 deg C on May 5 in the eastern part of the country.
The lowest daily minimum temperature recorded here since records started in 1929 was 19.4 deg C on Jan 30 and 31, 1934.
Weather scientist Koh Tieh Yong said this could be due to the "sunshade" effect of thick storm clouds.
He said: "The thick storm clouds behave like giant sunshades that cut down sunlight that otherwise would have warmed the surface. Meanwhile, acting like a giant mist-blowing fan, the winds are continuously cooled by the evaporation from falling raindrops."
The associate professor at the Singapore University of Social Sciences added that Singaporeans should continue to expect low temperatures.
"On average, December and early January have the most rainfall with the strongest winds and the shortest sunshine duration compared with the rest of the year," he said.
October, which had thundery showers on most days of the month, also experienced some chilly weather with temperatures dipping below 22 deg C in some parts, including Khatib, on some days.
The MSS forecast for the first two weeks of December noted that the colder weather this month is partly due to the moderate to heavy thundery showers expected.
This comes amid the wet phase of the north-east monsoon season between December and January, which could see monsoon surges bringing several days of widespread continuous rain across the island.
On Monday, intense rain brought flash floods that disrupted traffic in Jurong East Street 32 and Choa Chu Kang Avenue 1, national water agency PUB said.
A tree also fell on a car parked in a Bedok North housing estate and uprooted a metal railing that was in its path.
The MSS predicts that temperatures will range from 23 deg C to 31 deg C over the next 24 hours with windy conditions and periods of showers, occasionally with thunder.
- Additional reporting by Clara Chong