Updated at 1.56pm: Heavy rain lashed Hong Kong early on Tuesday ? causing visibility problems for motorists and delaying ferries. Many commuters sought refuge under balconies or inside shops and buildings as they tried to avoid being drenched. The Hong Kong Observatory said the heavy rain resulted from an ?active southwest monsoon?, which brought more than 70mm of rainfall to Tsuen Wan, Tsing Yi, Kwai Chung, Sha Tin and Sai Kung. The Observatory issued a thunderstorm warning at 7.05am, saying ?scattered, squally thunderstorms were expected to occur over Hong Kong?. Ferries and traffic were delayed by the bad weather but there were no reports of weather-related accidents by early Tuesday afternoon. Senior scientific officer with the Observatory Edwin Lai Sau-tak told local radio he expected the heavy rain would continue for a few more hours. The Observatory also said ?scattered heavy showers and thunderstorms? would continue for the rest of the week. Traffic police were urging motorists to take extra care because of the bad weather. A spokesman advised motorists to reduce speed and extend the distance between themselves and vehicles in front. Twice the normal stopping distance would be needed. He said motorists should also turn on headlights to improve their visibility while driving and pay careful attention to changing lanes. ?Pedestrians need to pay particular attention when crossing roads, especially at busy junctions or when their view was obstructed,? the spokesman added. Meanwhile, red flags have been hoisted in a number of beaches in the territory due to large waves which were considered dangerous. The beaches include: Turtle Cove Beach, St Stephen?s Beach and Chung Hom Kok Beach in Southern District, Hong Kong Island, Pui O Beach, Lower Cheung Sha Beach, Lo So Shing Beach and Hung Shing Yeh Beach in Islands District. June is traditionally the typhoon season in Hong Kong. In the past the territory has been hit by some powerful tropical cyclones. In 1999, Typhoon York led the Observatory to raise the No 10 signal for 11 hours. When this signal is issued, it means that winds of hurricane force ? 118km per hour or more ? are expected to affect the territory.