The Observatory on Saturday said the Standby Signal No 1 will remain in force until at least 5 pm as tropical cyclone Kajiki is steadily moving westwards and intensifying gradually.

At noon, the storm was about 560 kilometres south-southeast of Hong Kong.

The Observatory said the storm will move towards waters south of Hainan in the next few days and skirt around Hong Kong from Saturday night.

"Kajiki is expected to skirt around 500 kilometres or more to the south of Hong Kong tonight and tomorrow morning," senior scientific officer Lee Shuk-ming said.

"Winds will be occasionally strong over the southern part of the territory and the adjacent waters by then."

The weather will remain fine and very hot on Saturday afternoon, Lee said, with a few showers and squally thunderstorms hitting the city later in the day as Kajiki's outer rainbands edge towards the coast of Guangdong.

The SAR will also experience occasional squally showers and stronger winds on Sunday.