This is the terrifying moment a roof was torn off a building and sent flying as Typhoon Wipha approached Vietnam.

Footage shows a vehicle driving through fierce winds when suddenly a sheet of roofing was blown away, narrowly missing a van ahead, on July 20.

Another clip shows powerful gusts battering the roadway in Hanoi a day earlier, forcing drivers to stop as debris blew across the street.

Several motorcyclists were toppled by the strong winds, and a street vendor's cart was pushed into the road.

Wipha was expected to reach Vietnam's northern coast on the morning of Tuesday, July 22.

Authorities placed nearly 350,000 soldiers on standby, as the weather bureau warned of up to 50 cm (20 inches) of rainfall, enough to trigger floods and landslides.

After making landfall in the provinces of Hung Yen and Ninh Binh, Wipha was expected to weaken into a low-pressure system by Tuesday night.

On July 19, a tourist boat was capsized by the storm, leaving dozens of passengers dead. The vessel reportedly overturned after being hit by choppy waves and heavy rain off the coast of Ha Long Bay shortly after 2 pm local time.

Wipha has been downgraded to a tropical storm after hitting mainland China on July 20.