The weather bureau also issued warnings of medium- heavy rains and thunderstorm in the Central Highlands and the Central regions from September 21- 27.
The highest temperature in the area is measured between 27 degrees Celsius and 30 degrees Celsius.
At this time, the Southern region is expected excessive downpours, cyclone, lightning, hail and violent winds.
Next week, the upstream floodwater level on the Mekong River is forecast to recede gradually.
By September 25, the highest water level at Tien River’s Tan Chau station will reach 3.45 meters below alert level 1; meanwhile, the highest floodwater level at Hau River’s Chau Doc station will reach 2.85 meters below alert level 1.
The high risks of flooding and landslide are forecast in low- lying areas along riverside and outside embankments in the Mekong Delta provinces of An Giang and Dong Thap.
From September 23, a cold wave is going to hit the Northern region with an average temperature of 18- 20 degrees Celsius in the mountainous area.