According to the National Centre for Hydro-Meteorological Forecasting, the northern delta and Lang Son are forecast to receive 30-60 mm of rain from the night of August 30 through August 31, with more than 130 mm possible in some areas.
From August 31 to September 1, rainfall of 50-100 mm is forecast from Thanh Hoa to Hue, with some areas receiving more than 180 mm. Rainfall intensity could exceed 100 mm within three hours.
On August 30, areas from Thanh Hoa to Quang Tri are expected to receive 10-30 mm of rain, with localised totals above 70 mm.
The Central Highlands and southern Vietnam are also forecast to see showers and thunderstorms, mainly in the afternoon and evening, with rainfall of 10-30 mm and localised totals above 60 mm.
Weather forecasters warned that heavy rain could cause flooding in low-lying and urban areas, as well as flash floods on small rivers and streams and landslides on steep slopes.
Thunderstorms could also bring whirlwinds, lightning, hail and strong gusts.
Hanoi is forecast to be sunny during the day on August 30 before moderate rain and thunderstorms develop at night, with locally heavy downpours. Temperatures are expected to range from 25-27 degrees Celcius to highs of 33-35 degrees Celcius.
Hot weather is forecast along the south-central coast, with daytime temperatures of 34-37 degrees Celcius and above 38 degrees Celcius in some areas.
At sea, strong winds and rough conditions are expected across several areas. Waves of 2-4 metres are forecast in parts of the East Sea and waters from Khanh Hoa to Vinh Long.
Strong southwesterly winds and waves of up to four metres are expected to persist in several offshore areas on August 31, posing risks to vessels.