The observatory says it expects to issue the Standby Signal No 1 on Wednesday morning.

This comes as Tropical Cyclone Podul is forecast to come within 800 kilometres of Hong Kong.

The weather forecaster on Tuesday said it expects Podul to make landfall in eastern Guangdong or southern Fujian on Thursday.

It said it could consider issuing a higher warning signal later on Wednesday or early Thursday, depending on the storm's distance from the Pearl River Estuary, its intensity and the change in local winds.

The observatory added that the SAR will see occasional squally heavy showers and thunderstorms on Thursday.