The mercury will even drop to below 18C in some areas as cold air begins to affect the northeast and later other parts in the north and the north central provinces.
Cold air and the remnants of tropical storm Lionrock are expected to bring torrential rain to the northern and north-central regions.
The capital of Hanoi is also forecast to experience heavy to very heavy rain until October 11 while the lowest temperatures are expected to drop to around 20-22C.
Medium to heavy rain is also forecast for parts of the Central Highlands and the southern region due to the effect of the southwest seasonal winds.
There is a risk of flash floods and landslides in mountainous areas and localised flooding in low-lying and riverside areas.
In the Gulf of Tonkin, the sea is very rough with waves reaching heights of 3-4 metres, and wind speeds reaching 90 kilometres per hour with gusts of up to 117 kilometres per hour.
Strong winds are also expected in the coastal area from Quang Ninh Province to Nghe An Province.
