The Chinese National Observatory has issued its highest level storm warning for super typhoon Usagi.
According to data from the Observatory’s storm tracker Usagi is now heading straight for the city of Hong Kong.
Experts say it is likely to be the strongest typhoon to hit the city this year.
Airlines Cathay Pacific and Dragonair announced Saturday they would halt all flights in and out of Hong Kong from 6pm Sunday, as Super Typhoon Usagi roared towards the city.
After brushing past the Philippines and Taiwan, the huge storm continued on its path towards Southern China, with forecasters predicting it will reach Hong Kong in the early hours of Monday morning.
A statement on Cathay Pacific's website read: "Due to the anticipated impact of Super Typhoon Usagi approaching, the operations at Hong Kong will stop from 18: 00 on 22 September (Sunday) through 23 September (Monday).
"The airline is monitoring the situation closely and will issue further advice on the resumption of flight services. It is anticipated that disruptions will continue on 23 September due to the impact of adverse weather and operational constraints.
"You are encouraged to defer non-essential travel on Sunday 22 September to Monday 23 September."
In Hong Kong, officials warned the storm posed a "severe threat" to the city, urging residents to brace for strong winds and possible flooding.
The Hong Kong Observatory cautioned engineers and builders to secure scaffoldings, window-panes and other temporary structures in a statement issued Saturday afternoon. It also warned that storm surges induced by Usagi might also lead to flooding in low-lying areas on Sunday night.
China's National Meteorological Center issued a red alert - its highest level warning - as it forecast gale-force winds and heavy rain.
It said Usagi would affect the coastal areas of the provinces of Guangdong, Zhejiang and Fujian as it moved northwest.
Nearly 23,000 fishing boats had earlier taken shelter in Fujian province ahead of the storm, state media reported Saturday, while more than 4,000 people living in coastal areas were evacuated.
Usagi brought torrential rain and strong winds to the Philippines and Taiwan Saturday, uprooting trees and knocking out power as it barrelled towards Hong Kong.
The typhoon battered the Batanes island group in the far north of the Philippines overnight with gusts of up to 250 kilometres (155 miles) per hour, affecting communication lines and damaging crops, officials said.
"The winds are very strong. I cannot even go out now," Batanes governor Vicente Gato told DZBB radio in Manila. "Many trees have been uprooted and we have no electricity," he said.
The National Disaster Risk Reduction and Management Center issued its highest alert, with flooding recorded in four regions of the main island of Luzon, the country's most populous area, while several roads and bridges were rendered impassable by overflowing rivers or landslides.
There were no immediate reports of any casualties, although emergency and relief services said they were prepared for the worst with more than 100 families having already been evacuated in one northern province.
In Taiwan, some flights were cancelled and ferry services suspended, with schools and offices in many parts of the island closed, especially in the south and east, which were expected to bear the brunt of the storm, authorities said.
Coastguards cordoned off the beaches at Kenting, a popular scenic spot in the south, as strong winds whipped up the sea.
The defence ministry has deployed more than 1,600 soldiers to "high risk" areas and placed 24,000 others on standby.
Nearly 2,500 people had already been evacuated, officials said, as the Central Weather Bureau warned people to expect up to 1.2 metres (47 inches) of rain. Hotels and resorts in mountainous areas were closed due to fears of flooding and landslides.
The US Navy's Joint Typhoon Warning Center said that Usagi was packing sustained winds of 240 kilometres per hour (150 miles per hour) with gusts of nearly 300 kilometres per hour, making it the equivalent of a strong category four Atlantic hurricane.
As of 0400 GMT on Saturday, Usagi was still roaring through the Luzon Strait separating the Philippines and Taiwan, heading directly for the southern Chinese coast.
The region is regularly pummelled by tropical storms. Typhoon Bopha left a trail of destruction in the southern Philippines last year, triggering floods and landslides that left more than 1,800 dead and missing and displaced nearly one million people.
In August 2009, Typhoon Morakot killed about 600 people in Taiwan, most of them buried in huge landslides in the south, in one of the worst natural disasters to hit the island in recent years.
Hong Kong rarely suffers major loss of life as a result of tropical storms, although Typhoon Rose in 1971 killed 110 people in the city.
China's national observatory on Saturday issued the highest level of alert for super typhoon Usagi, upgrading its warning to the red from the previous yellow-coded one issued yesterday afternoon. Hong Kong Observatory has issued a T1 warning at 10:40 am on Saturday.
It issued a very hot weather warning yesterday, and the heat and haze is likely to continue today. Heavy squally showers, strong winds and rough seas were expected tomorrow and on Monday, with Usagi forecast to be closest to the city tomorrow night, it said.
Xinhua reported that Chinese authorities on Friday had issued a disaster relief alert ahead of the typhoon which it said was expected to hit coastal regions of southern China’s Guangdong Province on Sunday.
As of 8am on Saturday, Super Typhoon Usagi was centred about 680 kilometres north-northeast of Manila. It is forecast to move northwest or west-northwest at about 18 kilometres per hour across the western North Pacific in the general direction of the Luzon Strait.
Winds of 205 kilometers per hour were expected to bring torrential rain and destructive gusts. Philippine weather bureau forecaster Alvin Pura said the super typhoon had gathered strength and speed with gusts reaching 240 kph.
“It is the strongest typhoon in the west Pacific region this year,” a weather forecaster at the Taiwan Central Weather Bureau said. "Usagi is this year's most powerful tropical storm by wind speed anywhere in the world," Cheng Ming-Dean, director of Taiwan’s Weather Bureau added.