The Hong Kong Observatory issued the No. 1 typhoon warning signal at 12:20 pm on Friday as an area of low pressure over the northeastern part of the South China Sea has intensified into a tropical depression.

The signal No. 1 will remain in force for most of Friday, the forecaster said in a 1:45 pm bulletin.

It will be very hot in Hong Kong on Friday and in the next couple of days, with temperatures reaching 35 degrees or above in some areas. High temperatures will also trigger showers and squally thunderstorms, according to the HKO.

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At 1 pm, the tropical depression was estimated to be about 560 kilometers southeast of Hong Kong and is forecast to move northwest or west-northwest slowly, lingering over the northeastern part of the South China Sea.

“The circulation of the tropical depression is relatively small. It will be slow-moving and maintain a distance of over 400km from Hong Kong for the rest of today.”

There will be swells in the next couple of days, the observatory warned, asking people to stay away from the shoreline and not engage in water sports.

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The tropical depression is expected to linger over the northeastern part of the South China Sea and intensify gradually on Friday and Saturday. It will then have a higher chance of turning northwards in the general direction of the vicinity of the Taiwan Strait to the coast of eastern Guangdong, said the forecaster.

“There are still uncertainties in its movement,” the HKO said, adding that it will assess the need to issue higher tropical cyclone warning signals later Saturday or Sunday, depending on the distance between the associated strong winds and the Pearl River Estuary and its intensification.