A cold front is moving from the south of China to the north of Viet Nam, according to the National Center of Hydrometeorology Forecasting.
The front will affect northern and north-central provinces, causing heavy downpours and thunderstorms from today. Temperatures can fall to between 20 to 27 degrees centigrade. Strong 7-force winds will render the seas in the area very choppy, the center says.
It also warns that mountainous regions in particular are likely to experience squall, whirlwinds and thunder.