The typhoon, which was packing wind speeds of up to 133km/h, is expected to make landfall in central Vietnam late on Sunday, earlier than previous forecasts as it was travelling fast, according to Vietnam's national weather forecast agency.
"This is a rapidly moving storm - nearly twice the average speed - with strong intensity and a broad area of impact. It is capable of triggering multiple natural disasters simultaneously, including powerful winds, heavy rainfall, flooding, flash floods, landslides, and coastal inundation," the agency added.
Authorities in the central province of Ha Tinh have started to evacuate more than 15,000 people, the government said, adding thousands troops were standing ready.
Vietnam suspended operations at four coastal airports from Sunday, including Danang international airport, and adjusted the departure time of several flights, the Civil Aviation Authority said.
Heavy rain has already caused flooding in Hue and Quang Tri, the government said.
With a long coastline facing the South China Sea, Vietnam is prone to typhoons that are often deadly. Last year, Typhoon Yagi killed around 300 people and caused $US3.3 billion ($A5 billion) of property damage.
