This is called the North East Monsoon. It usually rain at least 2X a day in Nov and by end Nov or early Dec, it can even rain for 1/2 day or sometimes for the whole day or even days. It will start to taper off by Jan but before it goes off, it will pour again usually in early Jan and late Jan
Bukit Timah used to get flooded during the monsoon some 20 years ago. Coronation Plaza is infamous for the frequently flooded underground carpark.
Good thing about the NE Monsoon is that it blow the haze away from us. Come May to Sep when the South West Monsoon is in season, it will not bring much rain but it will bring haze.