Vietnam has ordered more than 586,000 people to be evacuated ahead of the arrival of Typhoon Kajiki.
The storm is already packing winds of 166km/h (103mph) and is expected to strengthen further before making landfall early on Monday, weather forecasters said.
People from the central provinces of Thanh Hoa, Quang Tri, Hue and Da Nang have been ordered to leave their homes. Flights have been cancelled and boats told to stay ashore.
The storm is skirting past Hainan in China, where the country’s weather agency said up to 320mm (12.6in ) of rain was forecast.
BBC Weather says Typhoon Kajiki is expected to weaken as it moves inland into Vietnam, but still lash the country with winds of 200km/h and expected rainfall of 300-400mm.
Storm surges of 2-4m (6.6-13ft) are also expected.
Authorities have told people in the projected path not go outdoors after 14:00 GMT on Sunday. Soldiers have been deployed to help, they said.
“The situation is extremely dangerous and not safe for any vehicles or structures such as tourism or fishing vessels and aquaculture raising facilities,” AFP news agency quoted officials from the ministry of agriculture and environment as saying.
Vietnam Airlines cancelled at least 22 flights to and from central cities on Sunday and Monday.
Officials fear the storm could be as devastating as Yagi in September last year – a deadly typhoon which killed hundreds of people across the region, including 300 in Vietnam alone.
