According to NEA's website, the lowest temperature recorded in Singapore was 19.4 deg C on two days in 1934. Both days were in the month of January.
Monday, January 22, 2018
Singaporeans worry as temperature drops to low twenties
I lived in Singapore in the late nineties and I still sometimes look at the Singaporean news. The Straights Times has an article cautioning residents that the temperature has fallen into the low twenties Celsius.