The National Center for Hydro-Meteorological Forecasting said Storm Nakri, the sixth off the Vietnamese coast this year, lay centered 310 km north-northeast of Southwest Cay islet in Vietnam’s Spratly Islands as of 7 a.m. Wednesday.
It packed maximum wind speeds at the time of 75 kph.
Over the next 24 hours Nakri would move west at 5 km/h and could further intensify, the center said.
By 10 p.m. on Friday, the storm would be around 220 km from the Southwest Cay islet, carrying wind speed of 115 kph.
Nakri is expected to bring rain across south central and southeastern Vietnam until Saturday before weakening, according to U.S. weather forecasting website AccuWeather.
Japan Meteorological Agency and Hong Kong Observatory forecast that on Sunday, the storm's center position would be along south central Vietnam coast, with winds of 105 kph.
The Hong Kong station forecast that it would move across Vietnam and reach Cambodia on Monday.
The Central Steering Committee for Natural Disaster Prevention and Control and the National Committee for Incident, Natural Disaster Response and Search and Rescue have told authorities in provinces from Quang Tri to Ba Ria-Vung Tau to inform boats at sea about the storm so that they could seek shelter in time.
The area is home to popular destinations including Hue, Hoi An, Mui Ne and Nha Trang.
The south central region was just hit by storm Matmo last week. It felled hundreds of trees, damaging houses and causing widespread flooding in Phu Yen, Binh Dinh and Quang Ngai provinces.
Vietnam is hit by up to 10 tropical storms during the southwest monsoon season, usually between July and October.
There were nine last year.