In Quang Nam Province, the body of a 37-year-old woman who was swept away by floodwaters in Nui Thanh District on Monday afternoon was found later that day.
Authorities in Tam Ky Town said they are searching for a man who was reported missing on Monday night.
For the past two days Quang Nam has been battered by rainfall of up to 350 mm.
Neighboring Quang Ngai Province has also had heavy rains since Sunday night.
Many areas in its mountainous districts of Son Ha and Tra Bong have been flooded, with roads and bridges under around a meter of water on Monday.
A landslide occurred at the Ka Tinh hydropower plant in Tra Bong District at 6:30 p.m. Tuesday, leaving a worker missing.
Local authorities are trying to reach the scene.
The rains have been caused by a combination of the northeast monsoon and a cold spell from the north, according to the National Center for Hydro -Meteorological Forecasting.
It warned that until Tuesday flooding is likely in rivers from Ha Tinh to Quang Ngai provinces, with water levels rising by three to seven meters upstream and one to three meters downstream.
More flash floods and landslides should be expected, it warned.