According to the National Centre for Hydro-Meteorological Forecasting, the cold front began affecting northern mountainous areas on the morning of March 9 and is expected to strengthen later in the day.
The system will spread across northeastern areas before extending to the rest of northern Vietnam and the north-central region.
From the evening of March 9 to March 10, northern Vietnam and Thanh Hoa province are forecast to turn colder, with minimum temperatures ranging from 15-18 degrees Celsius. Mountainous areas could see temperatures fall below 14 degrees Celsius.
In Hanoi, scattered showers and isolated thunderstorms are expected during the day and night on March 9, with cooler conditions setting in from late evening into March 10.
Minimum temperatures in the capital are forecast at 16-18 degrees Celsius.
Forecasters also warned that from the night of March 8 to March 9, scattered rain and thunderstorms could occur across northern Vietnam, Thanh Hoa and Nghe An, with some areas experiencing heavy rainfall.
Rain in northern areas is expected to ease from March 10.
Meanwhile, from March 9 to March 10, areas from Ha Tinh to eastern Gia Lai are forecast to experience rain and scattered thunderstorms, with some localised heavy downpours.
The agency warned that thunderstorms could bring whirlwinds, lightning, hail and strong gusts of wind.