National Center for Hydro‑Meteorological Forecasts reported that a powerful tropical low, classified as level 6 with gusts at level 8, was situated about 160 km east of Da Nang on the night of 12 September. Moving northwest, the system was expected to make landfall between Hà Tĩnh and Quảng Trị on the night of 13 September, bringing prolonged heavy rain to the central region.
Observations on 12 September between 07:00 and 15:00 showed extreme totals: Bạch Mã (Huế) recorded 303.8 mm and Câu Lâu (Da Nang) 273 mm, with several stations exceeding 270 mm. Forecasts for 12‑15 September projected cumulative rainfall of 300‑600 mm across the central provinces, and localized amounts could surpass 800 mm, especially in Hà Tĩnh, Quảng Trị and Huế.
Rainfall distribution was detailed as follows:
- 12‑13 September: 50‑100 mm (up to 180 mm) in Hà Tĩnh, northern Quảng Trị and eastern Quảng Ngãi.
- 12‑13 September: 100‑200 mm (over 350 mm locally) in southern Quảng Trị and Da Nang.
- 13 September: Thanh Hóa and Nghệ An expected to receive 20‑40 mm, with isolated spots over 100 mm.
- 13‑14 September: 100‑200 mm band (exceeding 350 mm in places) shifted northward from Thanh Hóa to Quảng Trị.
- 14‑15 September: 30‑60 mm across the northern mid‑land and parts of the Red River basin, with some locations over 100 mm, while the southern Nghệ An‑Hà Tĩnh corridor could see 70‑150 mm, locally over 200 mm.
Soil‑moisture models indicated saturation levels above 85 % in the hardest‑hit provinces, raising the risk of flash floods, river overflows and landslides. Authorities issued disaster‑risk level 1 alerts for heavy rain, hail, tornadoes and landslides nationwide, and level 2 alerts specifically for Hà Tĩnh and Huế.
By 16 September, the heavy rain was expected to subside rapidly across the central region.