© Sam Tsang/SCMPPeople queue for public transport in Ma On Shan during today's rainstorm.
Hong Kong Observatory issued an amber rainstorm warning at 6.15am and warned residents of the chance of flash flooding in some places.
Pat Heung, Kam Tin and Sheung Shui in the northern New Territories were particularly badly hit after about 90 millimetres of rain fell in just two hours.
In Yuen Long rainfall exceeded 40 millimeters, while many other parts of the New Territories recorded 20 millimeters.
© SCMP Pictures
The Observatory issued a flood report at 6.40am, 25 minutes after the amber rainstorm signal. All the warnings have now been cancelled.
The amber rainstorm signal is issued when heavy rain has fallen or is expected to fall generally in the city, exceeding 30 millimeters in an hour and is likely to continue.
The Observatory said in a statement on its website, 'There will be flooding in some low-lying and poorly drained areas. People who are likely to be affected should take necessary precautions to reduce their exposure to risk posed by the heavy rain and flooding.
'Heavy rain may bring about flash floods. People should stay away from watercourses. People who are likely to be affected by flooding should take necessary precautions to avoid losses. Please listen to radio or watch television for traffic conditions and further announcements on the rainstorm.'
The Observatory had forecast a cloudy Monday with heavy showers and squally thunderstorms following a trough of low pressure from Guangdong.
An Observatory spokesman said the rain would continue into Tuesday before growing patchy and clearing on Wednesday.
Comment: All around the world flooding, in particular flash flooding following torrential rainfall, is becoming more common and intense with new records being broken.
Keep informed on these increasingly chaotic and 'unprecedented' events by viewing the monthly SOTT Earth Changes Summary.
SOTT Earth Changes Summary - August 2015: Extreme Weather, Planetary Upheaval, Meteor Fireballs