Hundreds of flights have been cancelled in Hong Kong and the neighbouring Chinese province of Guangdong ahead of the arrival of Typhoon Saola.
Schools, businesses and financial markets have closed as the area prepares for the storm, which has winds of up to 125mph (200kph).
Three tropical cyclones have formed in the northwest Pacific Ocean and South China Sea.
Saola and Haikui were classified on Friday as typhoons, while Kirogi, the furthest from land, was categorised as a tropical storm.
Saola, which could make landfall on Friday night or Saturday morning, may be among the five strongest typhoons to hit Guangdong since 1949, Chinese officials said.
The Hong Kong Observatory classifies a super typhoon as one with a sustained surface-wind strength of 115mph (185kph), but elsewhere the mark is higher.
It is set to hit China’s southern coast between the cities of Huidong and Taishan, China’s National Meteorological Centre said.
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Hong Kong and Macau lie in the centre of that coastline.
Storm surges may raise sea levels by up to 10ft (three metres), as the typhoon makes landfall, the observatory warned, with the potential for “serious flooding”.
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All schools in Hong Kong were closed on Friday, the first day of a new term for many.
Hong Kong office worker Wai Yi said: “We can see that the eye of the typhoon will pass very close… I’m a bit concerned and hope it won’t cause too many casualties.”
The city saw crowds jostling over items at fresh food markets on Thursday and long queues at supermarkets as customers stocked up ahead of the storm.
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Cathay Pacific, the city’s main airline, axed all flights in and out of Hong Kong between 2pm local time (7am UK time) on Friday and 10am on Saturday.
All trains in and out of Guangdong province were suspended from 8pm on Friday to 6pm on Saturday, local time.
The cities of Shenzhen and Guangzhou had already closed schools and Shenzhen, a city of more than 17 million people, also ordered businesses and financial markets to shut from Friday afternoon due to the risk from the potentially destructive winds heading its way.
Many supermarkets in Shenzhen were set to close early and hundreds of flights were cancelled both there and in the nearby city of Zhuhai.
The Hong Kong-Zhuhai-Macau Bridge connecting the three cities was shut from 3.30pm local time on Friday.
Typhoon Haikui is expected to make landfall in the northern part of Taiwan on Sunday before heading towards the southeastern Chinese city of Fuzhou, the island’s Central Weather Bureau said.