The Hong Kong Observatory said it will cancel the Standby Signal No. 1 at 2.20pm on Thursday, as a tropical depression weakens gradually and departs from the region.

As of noon, the tropical depression was about 430 kilometres west-southwest of Hong Kong.

Its threat to Hong Kong will diminish in the afternoon as it moves into the inland areas of Guangxi.

"In the past few hours, squally showers associated with the tropical depression continue to affect the coast of Guangdong," acting senior scientific officer Kok Mang-hin said.

"Locally, over 20 millimetres of rainfall were recorded over parts of the territory this morning, with occasional strong winds on high grounds.

"The rain bands associated with the tropical depression will still bring squalls to the territory today.

"There will be occasional showers and thunderstorms tomorrow."

The Standby Signal came into force at 2.20pm on Wednesday.