The National Centre for Hydro-Meteorological Forecasting said widespread rainfall would intensify across northern and central regions over the three-day period, increasing the risk of flooding, flash floods and landslides.
In Hanoi and many other northern localities, heavy rain is expected to expand across the region from September 14. The Red River Delta, the northern midlands and the provinces of Son La, Phu Tho, Tuyen Quang and Lao Cai are forecast to receive between 70mm and 150mm of rainfall, with some areas exceeding 200mm.
Hanoi is forecast to see heavy to very heavy rain on September 14 (Photo: Nguyen Hai).
Forecasters warned that exceptionally intense downpours could occur during the period, with rainfall surpassing 100mm within just three hours in isolated locations.
From Thanh Hoa and Nghe An southwards to Quang Tri, cumulative rainfall is expected to range between 250mm and 450mm, while some localities could record more than 600mm.
Meteorologists said the severe weather could trigger widespread flooding in low-lying areas, flash floods along rivers and streams, and landslides in mountainous regions.
Authorities also warned residents to remain alert for thunderstorms accompanied by tornadoes, lightning, hail and strong gusty winds.