The Ca Mau Hydrometeorological Station said widespread rain was forecast from May 29 to June 8, with moderate to heavy rainfall and isolated areas expected to see very heavy downpours.
Rain is forecast mainly during the afternoon, evening and night, with rainfall likely to exceed 50mm within 24 hours in some areas, particularly between May 29-June 1 and June 5-8.
Forecasters warned that thunderstorms could bring whirlwinds, lightning and strong winds capable of damaging homes, uprooting trees and threatening human safety.
The agency also cautioned that heavy rain coinciding with high tides during the full moon period of the fourth lunar month could trigger flooding in low-lying areas, as well as landslides and land subsidence affecting production and daily life.
At sea, the southwest monsoon is expected to strengthen over waters off Ca Mau Province, bringing scattered showers and thunderstorms.
During storms, whirlwinds, lightning, gusts of up to force 6-7 and waves exceeding 2 metres could threaten vessels and maritime activities, the agency said.
Earlier on May 24, thunderstorms and whirlwinds struck several wards and communes in Ca Mau Province.
Preliminary reports showed more than 90 houses were damaged, including seven that collapsed completely, while many others lost roofs. Trees and power lines were also damaged.