The National Centre for Hydro-Meteorological Forecasting said northern Vietnam and the Thanh Hoa-Ha Tinh area would experience moderate to heavy rain and thunderstorms from the night of August 17 through August 18.
An image of severe flooding in Hanoi in October 2025 (Photo: Son Nguyen).
Rainfall is expected to reach 30-60mm in most areas, with isolated downpours exceeding 100mm. Forecasters warned that some storms could produce more than 100mm of rain within just three hours.
Heavy rain is forecast to continue from the night of August 18 through August 21 across northern Vietnam and the area from Thanh Hoa to northern Quang Tri, with rainfall of 120-250mm in many areas and isolated totals above 350mm.
In Lai Chau, Dien Bien, northern Tuyen Quang, Cao Bang, Lang Son and northern Quang Tri, rainfall is expected to range from 80mm to 170mm during the period, with isolated areas receiving more than 230mm.
Overall, from the night of August 17 through the end of August 21, northern Vietnam and the area from Thanh Hoa to northern Quang Tri could receive 150-300mm of rain, with isolated totals exceeding 450mm.
In Lai Chau, Dien Bien, northern Tuyen Quang, Cao Bang, Lang Son and northern Quang Tri, accumulated rainfall is forecast at 100-200mm, with isolated areas receiving more than 300mm.
Meanwhile, the Central Highlands and southern Vietnam are expected to see showers and scattered thunderstorms, with rainfall of 15-30mm and isolated totals above 60mm.
The weather agency warned that heavy and locally intense rain could cause flooding in low-lying areas, urban centres and industrial parks.
Residents in mountainous areas have also been advised to remain alert for flash floods in rivers and small streams, as well as landslides on steep slopes.