The Observatory said, “Tropical Cyclone Nangka will move in the general direction of the vicinity of Hainan Island today and gradually intensify.
“Under the combined effect of Nangka and the northeast monsoon, there will be high winds, heavy rains and thunderstorms on the south coast of China on Tuesday and Wednesday.”
Winds of 73 km / h were recorded over Waglan Island in Hong Kong.
The Hong Kong government has reportedly opened 26 temporary shelters for residents.
Nangka is the second N.8 storm to be reported by the city this year.
Typhoon Higos was the first No. 8 reported this year from Hong Kong in August.
It brought strong winds and was elevated to No.9, the second highest in the weather system.
Four temporary COVID-19 test centers in the city have closed due to inclement weather.
The Hong Kong education bureau said classes at all day schools will be suspended on Tuesday due to weather hazards.
According to the Observatory, the wind speed should remain high on Wednesday with heavy showers.
But heavy rains are expected to ease later in the week in Hong Kong.
Storm Nangka has already brought strong winds to the offshore waters, the weather agency said.
The Observatory said: “Nangka is gradually moving away from Hong Kong.
“However, under the combined effect of the northeast monsoon, local winds are expected to strengthen further.
“In particular, the southern part of Hong Kong will experience stronger winds.”
He added, “An upper high pressure system will strengthen in the latter part of this week, the rain will abate and the weather will improve on the Guangdong coast.
“Another tropical cyclone is expected to enter and pass through the central part of the South China Sea around the weekend, and will intensify further.”
Hong Kong has warned residents to avoid the shore due to inclement weather.