The observatory has warned of heavy rain and thunderstorms in the next couple of days after a tropical storm made another sharp turn in its path and began moving closer to the SAR again.
The forecaster on Wednesday said it might issue the Strong Monsoon Signal depending on changes to winds, as Tropical Depression Danas is moving across Fujian in a south-westerly direction.
"According to the present forecast, Danas will move west-southwest, enter Guangdong and weaken gradually [on Wednesday and Thursday]. Its remnants may then skirt near Guangzhou," it said.
"The active southwest monsoon to its south will generally affect the vicinity of the Pearl River Estuary [on Thursday and Friday]. There will be torrential rain and squally thunderstorms over the territory."
The weather is expected to be "relatively severe" because of the combined effect of the torrential rain and rather strong southwest monsoon.
Just days ago, Danas edged closer to Hong Kong and prompted the forecaster to issue the Standby Signal No 1, before the storm later made a sharp turn and moved away from the territory.