The Observatory issued the Strong Wind Signal No 3 on Saturday at 12.20 pm, saying it will remain in force at least until noon the next day, as strong winds from a severe tropical storm are expected to strengthen.

But the chance of it being raised to a No 8 signal is "rather low" unless Severe Tropical Storm Wutip maintains a higher intensity over inland areas and takes a track closer to the Pearl River Estuary, according to the weather forecaster.

Wutip was forecast to move northeast at about 22 kilometres per hour towards the Leizhou Peninsula.

"The strong winds associated with Wutip are expected to gradually prevail over the vicinity of the Pearl River Estuary. Winds will strengthen progressively over the territory, and up to gale force on high ground later," the Observatory said.

The Education Bureau announced that classes of kindergartens, schools for children with physical disability and schools for children with intellectual disability were suspended.

"These schools, however, should keep their premises open and implement contingency measures to look after arriving students. They should ensure that conditions are safe before allowing students to return home," the bureau said.

Several ferry routes to and from outlying islands, as well as the Ngong Ping 360 cable car service, also stopped operations.

According to the forecast, Wutip will move further inland and weaken and local winds are expected to "moderate progressively" on Sunday.

While the severe tropical storm will depart and dissipate on Monday and Tuesday, the Observatory warned that there will be heavy showers along the coast of Guangdong due to an active south-westerly airstream.