From 4.20 pm to 10.20 pm on September 28, rainfall of 15-35 mm was forecast across Khanh Hoa, with some areas receiving more than 70 mm. Lam Dong was expected to receive 10-30 mm, with isolated totals exceeding 60 mm.
The rainfall could trigger flash floods along small rivers and streams and landslides on steep slopes in several communes and wards across the two provinces.
In Khanh Hoa, areas at risk include Tay Khanh Son, Bac Ai, Bac Ai Dong, Bac Ai Tay, Khanh Son, Khanh Vinh, Lam Son, Nam Khanh Vinh, Tay Khanh Vinh and Trung Khanh Vinh.
In Lam Dong, warnings cover Nam Ban Lam Ha, Bao Thuan, Dak Mil, Dak Sak, Dam Rong 2, Dam Rong 3, Dinh Van Lam Ha, D'Ran, Hiep Thanh, Krong No, Lac Duong, Nam Da, Nam Ha Lam Ha, Nam Nung, Phu Son Lam Ha, Phuc Tho Lam Ha, Quang Phu and Tan Hoi.
The natural disaster risk level for flash floods, landslides and rain-induced ground subsidence has been set at Level 1.
Authorities warned that flash floods and landslides could threaten lives, disrupt traffic and damage property, urging checks of vulnerable areas and blocked waterways.
Heavy rain had already been recorded on September 28, including 80.8 mm at Thanh Son 3 in Khanh Hoa and 73 mm at Lac Xuan-Don Duong and 64 mm at Nam Ban in Lam Dong.
Soil moisture models showed some areas of Khanh Hoa were close to or had reached saturation, increasing the risk of landslides.