The observatory on Tuesday said it would cancel all tropical cyclone warning signals at 6.20pm, as Severe Tropical Storm Fengshen continued to move away from Hong Kong as it headed towards Vietnam.

The Strong Wind Signal No 3 was issued on Monday afternoon.

The observatory warned, however, that local winds were still strong.

"Under the influence of the outer rainband of Fengshen and the northeast monsoon, temperatures over the territory are falling progressively. Local weather is expected to be further dominated by the monsoon later," a statement said.

The forecaster called on the public to stay away from the shoreline and not to take part in water sports.

It also warned that sea levels would generally be 0.5 to 1 metre higher than normal on Tuesday night and in the following days.

"Flooding may occur over some low-lying coastal areas during the high tides at night. The water level over Victoria Harbour will rise to around 3 metres above Chart Datum," the observatory said.