From September 22 to October 20, moderate to heavy rain is likely across the northern delta and central Vietnam, while the Central Highlands and southern regions could see frequent showers and thunderstorms, including periods of moderate to heavy rain.
Cold air is also expected to continue affecting northern Vietnam and the north-central region, according to the National Centre for Hydro-Meteorological Forecasting.
Tropical storms and depressions in the East Sea and those making landfall in Vietnam are expected to be less frequent than the long-term average. The East Sea typically sees 2.2 storms or tropical depressions during the period, with one making landfall in Vietnam.
Nguyen Duc Hoa, deputy head of the centre's climate forecasting division, said average temperatures nationwide were expected to be 0.5-1.5 degrees Celsius above normal, with higher anomalies possible in some areas.
Thunderstorms, tornadoes, lightning, hail and strong gusts could also occur across the country, he said.
Northern Vietnam is forecast to receive 70-170 mm of rain in October, while rainfall elsewhere is expected to be 5-20 per cent below average, widening to 20-40 per cent in parts of central Vietnam and the Central Highlands.
Rainfall in November is forecast to be 10-30 per cent above average in the north and from Thanh Hoa to Ha Tinh, but 20-40 per cent below average from Quang Tri to Lam Dong and 5-15 per cent below average in southern Vietnam.
In December, rainfall in the north and from Thanh Hoa to Ha Tinh is expected to be 5-20 mm above average, while most other regions could receive 5-20 mm less than normal. The south-central coast could see deficits of 50-100 mm.
Weather experts warned that the convergence zone, southwest monsoon and cold air could bring widespread rain, thunderstorms, hail and strong winds.
The weather agency advised residents and authorities to closely follow short-term forecasts and warnings as conditions could change rapidly.
