SINGAPORE - Last week's cool spell was the longest in the Republic for at least a decade, weather experts said on Thursday (Jan 18).
"In the last 10 years, there was no cold spell of five days or more with minimum temperatures between 21 deg C and 22 deg C," the Meteorological Service Singapore (MSS) told The Straits Times.
"Over this period, most monsoon surges that affect Singapore are of short duration lasting two to three days."
The five days of cool weather, which lasted from Wednesday to Sunday, delighted many locals and was a result of a monsoon surge.
Monsoon surges, which are common from December to March, are sudden increases in wind speed, which bring in cool air from the winter chill in the northern hemisphere.
As this cold air moves south, it warms and gathers moisture, resulting in rain over the equatorial region, including in Singapore.
Last week's surge led to five days of cool but rainy weather, leading some people to break out their winter wear and spurring heart-warming acts of kindness. Restaurant owner Francis Ng, 44, for example, bought blankets to distribute to seniors who sleep on the streets.
Satellite images showed that wind speeds picked up significantly last Wednesday as temperatures in Singapore fell to 22.8 deg C. The surge continued until Sunday, when temperatures in Jurong West and Admiralty dropped to a low of 21.2 deg C - the lowest temperature recorded in Singapore since 2016.
The mean daily temperature range for January is between 24 deg C and 30 deg C, according to the Met Station's long-term climate records dating from 1982.
Such cool spells could become more frequent due to climate change, the MSS spokesman said. Projections for 2100 made by MSS' Centre for Climate Research Singapore show that there could be more rain from cold surges during the north-east monsoon season.
"This indicates a possibility of more intense surges with higher risk of extreme weather," the spokesman added.
Experts have warned that more extreme weather is on the cards for Singapore as the world warms. This includes heatwaves, prolonged dry spells and periods of more intense rainfall.
There are already tell-tale signs of this, apparent in MSS' report of the weather and climate in 2017 released last Thursday.
Singapore broke another temperature record last year, with a mean annual temperature of 27.7 deg C. This made 2017 the warmest year on record that was not influenced by El Nino - a weather phenomenon associated with hot and dry weather in this part of the world.
While the mean annual temperature in 2017 was lower than the 28.4 deg C in 2016, and 28.3 deg C in 2015, those two years were influenced by El Nino.
Very warm days were also experienced in Singapore last year despite it not being an El Nino year, with the normally cool months of January and December also seeing warmer than usual temperatures on some days, the MSS said.
Heavy rain from intense thunderstorms caused flash floods and fallen trees. A waterspout - associated with thunderstorm clouds - was also observed off Singapore's southern coast last June. February, usually a dry season, saw twice the amount of rain compared with the long-term average.