The Hong Kong Observatory issued the amber rainstorm warning at 11pm on Wednesday, saying that widespread heavy rain may affect Hong Kong in a few hours.

The signal comes as Tropical Cyclone Danas moves across Fujian. It is forecast to move southwest, weaken gradually, and enter Guangdong on Thursday.

"There will be torrential rain and squally thunderstorms over the territory," the forecaster said on its website.

"Meanwhile, the Observatory will consider issuing the Strong Monsoon Signal depending on the local wind change," it added.

It had said the weather would be "relatively severe" in the region under the combined effect of the torrential rain and rather strong southwest monsoon.

Just days ago, Danas edged close to Hong Kong and prompted the issuance of the Standby Signal No 1.