The Observatory said it will consider issuing the Standby Signal No 1 on Thursday morning if an area of low pressure develops into a tropical cyclone and reaches within 800 kilometres of Hong Kong.

The forecaster said on Wednesday afternoon that the low pressure area has entered the central and northern parts of the South China Sea and is expected to move towards Hainan.

"However, there are uncertainties in its intensity," the Observatory said.

“Unless the low pressure system intensifies significantly, or adopts a track closer to the coast of Guangdong, the chance of persistent strong winds generally over the territory is expected to be relatively low,” it added.

The Observatory said earlier it would consider issuing the No 1 between Wednesday night and Thursday morning if an area of low pressure develops into a tropical cyclone.

The forecaster said there will be heavy showers at times on Thursday, as well as thunderstorms and squalls.