According to the National Centre for Hydro-Meteorological Forecasting, widespread heavy rain was being driven by strengthening cold air, the intertropical convergence zone and disturbances in upper-level easterly winds.
From overnight to early October 6, heavy to very heavy rain hit areas from southern Ha Tinh to Hue, with rainfall exceeding 250 mm in some locations. Ky Anh in Ha Tinh recorded 297 mm, while Sen Thuy in Quang Tri received 248 mm.
From October 6-8, heavy rain is forecast from southern Quang Tri to eastern Quang Ngai, with widespread totals of 100-200 mm and more than 300 mm in some areas.
Hue and Danang are expected to bear the brunt of the rainfall, with totals of 200-400 mm and locally more than 600 mm. The disaster risk warning for heavy rain in the two cities has been raised to Level 2.
Rainfall from Hue to eastern Quang Ngai is expected to ease from the night of October 8, but the rain band is forecast to shift northwards and could extend as far as Thanh Hoa.
Forecasters said the heavy rain could persist until October 11, increasing the risk of severe flooding in low-lying and urban areas, as well as flash floods and landslides.