The Observatory said it may consider issuing higher tropical cyclone warning signal on Sunday night, according to Tropical Storm Tapah's rate of intensification and proximity to Hong Kong.

The weather watchdog raised the Strong Wind Signal No. 3 at 2.40am, and said the signal would remain in force for most of the day.

The forecaster said the storm has continued to track north-northwestwards, with its outer bands of thundery showers affecting the coast of Guangdong.

Local winds will pick up progressively, it added.

"According to the present forecast, Tapah will continue to intensify and skirt around 200 kilometres to the southwest of Hong Kong tomorrow morning," said Acting Senior Scientific Officer Shum Chi-tai.

"Members of the public are advised to stay away from the shoreline and not to engage in water sports," he added.

The Observatory said heavy squally showers and thunderstorms will hit the city on Monday and Tuesday, with the weather improving and becoming very hot in the middle and latter parts of the week.