The Observatory said on Sunday that it would consider issuing the Standby signal number one later on Monday or on Tuesday, as another storm approaches Hong Kong.

Forecasters said an area of low pressure was expected to develop into a tropical cyclone by then.

Senior Scientific Officer Tong Yu-fai said it was still not clear how strong the storm would be or what track it would follow.

"It is likely to move towards the vicinity of western Guangdong and Hainan island, but the probability distribution is quite broad, also the world's major computer models disagree on the intensity prediction of the tropical cyclone," he explained during a briefing on Sunday.

He called on the public to brace for a deterioration in weather.

"The local weather will be windy with heavy squally showers and thunderstorms on Tuesday and Wednesday," Tong said.