At 7 a.m. Tuesday the tropical storm lay centered around 230 km east-northeast of Southwest Cay islet, and had winds of up to 165 kph, 30 kph higher than on Monday afternoon, according to the National Center for Hydro-Meteorological Forecasting.

The storm is moving westward at a speed of 25 kph, gradually intensifying, and is forecast to make landfall over Quang Nam, Quang Ngai and Binh Dinh provinces with winds of 165 kph.

It will then weaken and on Thursday become a low pressure area over eastern Thailand with winds of less than 40 kph.

The U.S. Navy forecast it would make landfall over Quang Ngai and neighboring Quang Nam at 1 p.m. on Wednesday with maximum winds of 120 kph.

Mai Van Khiem, director of the national forecast center, said: "This is the strongest storm to hit Vietnam since the beginning of this year."

He urged residents to limit outdoor activities from Tuesday night.

Authorities in Binh Dinh Province, home to the beach town of Quy Nhon, closed all beaches at 8 p.m. on Monday and banned vessels from going out to sea.

Quang Nam and Quang Ngai, home to beaches like An Bang, Cua Dai, Tra My and My Khe, also shut down public beaches and banned swimming in the sea.

Da Nang, Thua Thien-Hue and Phu Yen have taken similar actions.

Over one million students in central localities such as Quang Nam, Quang Ngai, Da Nang and Binh Dinh have been told to stay home on Tuesday and Wednesday.

Authorities are racing to evacuate over 1.2 million people in seven provinces, Ha Tinh, Quang Binh, Quang Tri, Thua Thien-Hue, Quang Nam, Quang Ngai and Binh Dinh, before the storm hits.

The region has been reeling from historic flooding and deadly landslides this month, with at least 130 people being killed so far.

Nham Xuan Sy, director of Quang Ngai Province's Center for Hydro-Meteorological Forecasting, said Ly Son Island has already been hit by strong winds.

"It is highly likely that Quang Ngai will be directly affected by the storm from Tuesday night."

He urged people to move to safety as soon as possible.

The storm combined with a cold spell would cause heavy rains, and localities from Nghe An to Phu Yen, a distance of over 1,000 km, will see torrential downpours and strong winds from Tuesday to Thursday.

Nghe An, Ha Tinh and Quang Binh have been warned the downpours will continue until Saturday and they are likely to get up to 700 mm. Rainfall of 180 mm a day is considered heavy.

Mountainous areas have been warned of a high risk of landslides.

Molave lashed the Philippines overnight Sunday with maximum sustained winds of 120 kph and caused flooding and landslides, leaving two dead and at least 12 fishermen missing, Reuters reported.