A new tropical low expected to form in the East Sea during the next few days could hit the central coast between Binh Thuan and Ninh Thuan Provinces, warns the Central Hydro-meteorology Forecasting Centre.
The low is likely to generate winds of up to force 9 on the Beaufort scale, about 120km/h, and deliver heavy rain from Thua Thien-Hue to Ninh Thuan coastal provinces and into the Central Highlands.
Rivers from central Quang Ngai to Ninh Thuan provinces are also likely to rise to the second highest danger level.
The National Flood and Storm Control Steering Committee wants fishing boat skippers and crews working off shore regularly warned of any risks.
At least eight people are already dead or missing in central Viet Nam from the recent Storm Noul, which has brought prolonged heavy rain and subsequent floods.
The latest deathtoll figure for Storm Noul takes the toll of dead and missing from the storm to 20.
Binh Dinh and Phu Yen provinces each recorded seven deaths. There were another three in Khanh Hoa.
The floods destroyed 200 houses and submerged another 13,500. A total of 239 classroomswere also submerged. Losses are estimated at more than VND143 billion ($8.4 million).
The disaster isolated thousands of people and thousands more were evacuated to higher ground.
The General Statistics Office reports 515 people either killed or missing in natural disasters so far this year.
More than 230,000ha of crops and 54,000ha of aquaculture ponds have been ruined; more than 1 million fowls killed and 4,700 houses destroyed. The total loss at VND11.5 trillion ($676 million).