The Hong Kong Observatory will issue the Strong Wind Signal No. 3 at 9.20 am on Friday, with local winds expected to strengthen as Tropical Storm Mitag moves closer to the territory.

The storm is expected to make landfall over eastern Guangdong on Friday evening, before taking a more westerly track towards the Pearl River Estuary – a predicted path that means Mitag would pass within 100 kilometres to the north of Hong Kong.

"Depending on the change in Mitag's intensity by that time, the distance of its gale winds from Hong Kong and the change in local wind conditions, the observatory will assess the need of issuing higher tropical cyclone warning signals," the observatory said in a statement.

Classes of all kindergartens, schools for children with physical disability and schools for children with intellectual disability have been suspended for the day.

Mitag was centred around 190 east-southeast of the territory as of 7am, and is expected to intensify slightly as it moves northwest at about 15 kilometres per hour.

Forecasters say the storm will bring more showers and squalls to the territory as winds pick up, while showers will be heavy at times on Saturday.

Members of the public have been advised to stay away from the shoreline and not to engage in water sports.

The T1 standby signal has been in effect since Wednesday evening.