Flash floods triggered by intense afternoon downpours caused disruption across western Singapore on December 4, 2025. Authorities urged motorists to avoid several roads in the west and southwest as drains and canals briefly overflowed under some of the heaviest rain recorded this month. National water agency PUB said flash floods occurred at Pandan Road, Pesawat Drive, Boon Lay Avenue (between Jalan Boon Lay and Boon Lay Drive), and the junction of Boon Lay Way and Corporation Road on Thursday afternoon. Here’s what we know.
What exactly caused the Dec 4 flash floods in Singapore?
Rain gauges in western Singapore logged about 113.4 millimeters of rain between roughly 1.45pm and 3.25pm—equivalent to more than a third of the average rainfall for the entire month of December. In fact, this lies within the top 2% of maximum daily rainfall records since 1978. The intense burst of rain temporarily overwhelmed parts of the drainage network, leading to impassable lanes for vehicles in some low-lying areas.
PUB used social media alerts to warm of flash flood risk and advised the public to avoid roads in the south, southwest, and west of Singapore ahead of and during the storm.
Meanwhile, quick response teams were deployed on site to direct traffic away from inundated lanes and assist motorists. Although, waters receded within about 30 minutes at some of the worst-hit spots. Plus, public transport continued operating but some bus services experienced delays and diversions.
The Meteorological Service Singapore has flagged the first half of December to have heavy thundery showers in the afternoon under prevailing northeast monsoon conditions. Meanwhile, total rainfall for the first fortnight of the month is forecast to be near average over most of the island. Although, intense rainfall can still occur leading to localized flash floods in Singapore. More to follow.
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