According to the National Centre for Hydro-Meteorological Forecasting, Thanh Hoa to Ha Tinh provinces are expected to receive 50-100mm of rain, with isolated areas seeing more than 200mm.
Quang Tri to Danang and eastern Quang Ngai are forecast to receive 40-80mm, with some areas exceeding 150mm. Intense downpours of more than 80mm within three hours are possible.
Scattered showers and thunderstorms are also expected across the northern delta and southern parts of Son La and Phu Tho, with rainfall of 10-20mm and isolated totals exceeding 50mm.
Southern Vietnam and Lam Dong Province could see 15-30mm of rain, with some areas receiving more than 80mm.
At sea, northeasterly winds of Beaufort force 5-6, gusting to force 7-8, are forecast over the northern East Sea, including the Hoang Sa (Paracel) Islands, with waves reaching 2-4 metres.
Waters from southern Quang Tri to Quang Ngai will experience similar winds, with waves of 1.5-2.5 metres. Winds are expected to weaken overnight.
Thunderstorms are also forecast across the Gulf of Tonkin, the Gulf of Thailand and other parts of the East Sea, including waters around the Truong Sa (Spratly) Islands, bringing risks of waterspouts, strong gusts and waves exceeding two metres.
On October 11, rough seas are expected to persist in the northern East Sea, with waves of 2-3 metres before winds gradually ease overnight.
The marine disaster risk level is set at 2, with authorities warning vessels operating in affected waters of dangerous winds and high waves.