A tropical storm heading towards Hong Kong will develop into a severe typhoon, possibly bringing strong winds and rain as it comes within 400km (249 miles) of the city later in the week, the Observatory has said.
Severe Tropical Storm Koinu formed on Saturday morning over the western North Pacific Ocean, southeast of Taiwan. It was positioned about 900km east-northeast of Manila in the Philippines as of 2pm on Sunday.
Koinu, which means puppy in Japanese, will move towards the Luzon Strait and intensify into a severe typhoon on Tuesday.
The typhoon will be within 400km of Hong Kong by Friday, with winds at the centre of the storm expected to reach 155km/h (96mph). Last month, Super Typhoon Saola had average wind speeds above 200km/h near its eye at one stage.
Saola wrought havoc on the city and left fallen trees, rubbish-strewn streets and flooded coastal communities in its wake.
The weather would become windier with showers arriving over the coast of Guangdong province in the latter part of the week, the forecaster said.
Meanwhile, an anticyclone was bringing mainly fine and very hot weather to southern China during the long weekend that combined the Mid-Autumn Festival and National Day holidays in Hong Kong. Temperatures over parts of the city rose to about 33 degrees Celsius (91 degrees Fahrenheit) around noon on Sunday.
The forecaster predicted the weather to be persistently very hot with sunny periods and one or two showers in the coming few days, before becoming unsettled in the later the week.