The Observatory issued the Strong Wind Signal No. 3 at 12.20 pm on Saturday, as severe tropical storm Matmo edged closer to Hong Kong.

The Strong Wind Signal No. 3 will remain in force at least until 10 pm tonight.

In a weather update, the Observatory also said it would assess the need for higher tropical cyclone warning signals tonight.

"At noon, severe tropical storm Matmo was estimated to be about 470 kilometres south-southeast of Hong Kong and is forecast to move west-northwest at about 25 kilometres per hour across the northern part of the South China Sea and intensify gradually," said Kong Yu-chau, an acting senior scientific officer at the Observatory.

"With Matmo edging closer, local winds will strengthen gradually this afternoon."

The Observatory warned that winds with mean speeds of 41 to 62 kilometres per hour are expected.

It advised people to stay away from the shoreline and not to engage in water sports.