People in the North and Northeast have been warned to brace for torrential rain between Wednesday and Saturday due to the influence of tropical storm Son-Tinh, which is strengthening over the South China Sea.
The Meteorological Department's storm warning, issued early Wednesday, said Son-Tinh packed a maximum sustained wind of 70 kilometres per hour and was moving westward at 35kph.
The storm was expected to hit the upper part of Vietnam on Wednesday evening, which could result in heavy rains as well as torrential downpours in some areas in the North and Northeast from Wednesday to Saturday.
People in the two regions were advised to be vigilant for possible flash flooding and forest runoff, which could be triggered by the storm.
In the South, the intensifying southwest monsoon would affect the Andaman Sea, the South and Gulf of Thailand from Wednesday to Sunday, and this could cause persistent rain and heavy downpours in some areas in the East, Central Plains and the South.
The monsoon could whip up waves up to three-metres high, the weather office warned. Fishermen should be cautious with strong waves possible, and small boats should stay ashore.
People living on the coast in the East and in the western part of the South should to be alert for inshore surges, and should monitor weather updates closely.