Hong Kong on Monday issued a cyclone warning, urging people to stay away from the shoreline and not to engage in water sports, as a tropical storm approaches.

Hong Kong Observatory said the No 1 standby warning has come into force in the region, meaning a tropical cyclone, which is currently centered within some 800 kilometers (497 miles) of Hong Kong, may affect the region.

The weather monitoring agency also asked fishing vessels and low-power vessels in the open sea to “seek shelter as soon as possible and be secured properly with moorings.”

Details released by the observatory said severe tropical storm Rai was “estimated to be about 480 kilometers (298 miles) south-southwest of Hong Kong.”

The storm, it said, is expected to move northeast at about 22 kilometers (13 miles) per hour across the northern part of the South China Sea.

“Locally, occasional strong winds are now prevailing over offshore waters and on high ground. ... According to the present forecast, Rai will edge closer to the coast of Guangdong.

“It will be closest to Hong Kong around noon tomorrow, skirting within about 200 kilometers south of Hong Kong,” the agency said.