According to the National Centre for Hydro-Meteorological Forecasting, widespread rainfall could occur across the country during the month, with the heaviest rain likely concentrated in central and southern regions.
Rainfall in northern Vietnam is forecast to be 15-30 per cent above the long-term average, while Thanh Hoa, Ha Tinh and southern Vietnam are expected to receive near-average rainfall. Other regions could see rainfall 20-40 per cent below normal.
Nguyen Duc Hoa, deputy head of the centre's climate forecasting division, said average temperatures nationwide were expected to be 1-2 degrees Celsius above the long-term average, except in the south, where temperatures could be 0.5-1 degree higher.
Tropical storms and depressions in the East Sea are forecast to be less frequent than usual. The long-term November average is 1.5 storms and tropical depressions, including 0.9 making landfall in Vietnam.
Cold air outbreaks affecting northern and central Vietnam are also expected to be weaker than normal.
However, thunderstorms, tornadoes, lightning, hail and strong wind gusts could continue to occur nationwide.
Meteorologists warned that the interaction of the intertropical convergence zone, upper-level wind convergence, the southwest monsoon and cold air could trigger widespread rain and dangerous weather.
At sea, strong winds associated with cold air, the southwest monsoon, tropical cyclones and localised thunderstorms could pose risks to vessels.
The weather agency urged authorities and residents to monitor short-term forecasts and warnings, particularly those covering the next one to three days, to adjust production plans and prepare appropriate safety measures.
October saw extreme rainfall and record temperatures
In October, northern Vietnam experienced two widespread rainfall episodes, including one on October 4-5 that brought 20-50mm of rain to many areas.
Some locations recorded more than 100mm, including 176mm in Dien Bien, 191mm in Kim Boi, Phu Tho Province, and 138mm in Viet Tri, Phu Tho Province.
Central Vietnam experienced three widespread rainfall episodes during the month.
A prolonged spell from October 4-15 brought 100-250mm of rain across much of the region, with 350-550mm recorded in areas between Hue and Quang Ngai. Some locations received even higher totals.
Several weather stations recorded daily or monthly rainfall exceeding historical levels for the corresponding period.
Northern Vietnam also experienced a widespread heatwave from September 28 to October 2, with temperatures generally reaching 35-37 degrees Celsius and exceeding 37 degrees in some areas.
Several stations recorded daily maximum temperatures above previous records for the same period.
Average temperatures across most of Vietnam in October were 1-2 degrees Celsius above the long-term average, rising to 2-3 degrees above normal in the north.
Some southern areas recorded temperatures 0.5-1 degree higher than average.
A total of 98 weather stations recorded monthly average temperatures matching or exceeding historical records for the corresponding period, including 87 stations in northern Vietnam.