The Observatory on Wednesday said it would issue the Strong Wind Signal No.3 between noon and 2 pm as Severe Tropical Storm Ma-on edges closer towards the Pearl River estuary.

The Standby Signal No.1 remains in force, after being issued at 9.10 pm on Tuesday.

At 5 am, the storm was about 580 kilometres southeast of Hong Kong and forecast to move west-northwest towards the western coast of Guangdong, while intensifying gradually.

The Observatory said local winds would strengthen tonight and that Ma-on was expected to be closest to Hong Kong on Thursday morning. It said the storm might skirt within about 200 kilometres of the SAR, and winds would strengthen further then.