The Hong Kong Observatory on Friday said the Standby Signal No. 1 will stay up until at least 6 am on Saturday.

Severe Tropical Storm Trami is expected to skirt about 500 kilometres to the south of Hong Kong on Saturday morning, it said.

The forecaster predicted strong winds in some areas, especially offshore and on high ground due to the combined effects of Trami and a northeast monsoon.

But It said local winds will not strengthen much because the prevailing winds will mainly be northerlies.

“Depending on the distance of strong winds associated with Trami from the Pearl River Estuary and the change in local wind conditions, the observatory will assess the need of issuing the Strong Wind Signal No. 3 during the day [on Saturday]," it said.

Local winds are expected to weaken on Sunday when Trami moves further away, the observatory added.