Northern Vietnam is forecast to experience heavy rain from the night of May 22 through the morning of May 24, with average rainfall ranging from 70 to 150 mm and some areas expected to receive over 250 mm, according to the National Centre for Hydro-Meteorological Forecasting.

The north-central region is also expected to see moderate to heavy rain and thunderstorms from the evening of May 23 to the night of May 24. Some areas may experience torrential downpours with rainfall between 40 and 100 mm and isolated spots exceeding 150 mm.

The heaviest rainfall is likely to occur in provinces such as Son La, Hoa Binh, Ha Giang, Tuyen Quang, Bac Kan, Thai Nguyen, Bac Giang, Cao Bang, Lang Son, Quang Ninh, and Haiphong.

Authorities have warned that rainfall intensity could reach or exceed 100 mm within one to three hours, significantly raising the risk of flash floods and landslides.

Since northern provinces have just experienced a previous round of heavy rainfall, mountainous areas in Bac Kan, Lao Cai, Lai Chau, Yen Bai, Ha Giang, and Tuyen Quang are particularly vulnerable. The soil in these areas is already water-saturated, making landslides a persistent threat. Residents are urged to remain vigilant to avoid casualties and property damage.

In addition to the rain, thunderstorms, lightning, strong winds, and hail are expected. Lightning strikes may cause trees and power pylons to fall, damage rooftops, and even result in fires or injuries.

From May 22 to May 25, rivers such as the Thao and Lo and smaller rivers in the northern region and Thanh Hoa Province may experience rising water levels with flood peaks 2 to 5 metres above current levels.