National Water Authority Warns 17 Provinces of Flooding Risk
Heavy rainfall across northern and eastern Thailand has prompted authorities to issue flood warnings for 17 provinces through August 21, with intense downpours expected as a monsoon trough strengthens.
The National Water Resources Office reported that Thailand is experiencing heavy rainfall in scattered areas as of August 19, 2025, at 7:00 a.m., with particularly intense downpours in the upper north, upper northeast, and eastern regions. Rain is expected to increase further in the north and northeast on August 20-21 as a monsoon trough moves through the area, supported by a strengthening southwest monsoon system. Rainfall records by region include Nan Province in the north with 238 millimetres, Nong Khai in the northeast with 42 millimetres, Ayutthaya in the central region with 35 millimetres, Trat in the east with 137 millimetres, Kanchanaburi in the west with 39 millimetres, and Nakhon Si Thammarat in the south with 98 millimetres.
The National Water Resources Office has issued a flood alert for August 19-21, 2025, due to the risk of heavy cumulative rainfall. At-risk areas include urban and municipal zones prone to recurrent flooding due to inadequate drainage, as well as areas vulnerable to flash floods, flash landslides, and riverbank overflows. Seventeen provinces are under watch: Mae Hong Son, Chiang Mai, Chiang Rai, Lampun, Lampang, Phayao, Phrae, Nan, Uttaradit, Tak, Nong Khai, Bueng Kan, Nakhon Phanom, Sakon Nakhon, Chanthaburi, Trat, and Kanchanaburi.
National water storage stands at 48,718 million cubic metres, representing 60% of capacity, while water consumption is at 24,599 million cubic metres or 43%. By region, the north holds 16,041 million cubic metres (58%), the central region 656 million cubic metres (35%), the east 1,533 million cubic metres (48%), the west 19,952 million cubic metres (70%), and the south 4,783 million cubic metres (62%). The northeast is reported at approximately 48% capacity.
Thirteen major water reservoirs currently hold less than 30% capacity or are below minimum control levels, including Mae Mok, Khwae Noi Bamrung Daen, Thab Salao, Pa Sak Cholasit, Krasiao, Ubol Ratana, Chulachomklao, Lam Takhong, Mun, Lam Nang Rong, Khlong Siyad, Nurabutdinther Chindha, and Prachuap. An additional 61 medium-sized reservoirs across the country also fall below the 30% threshold, distributed as five in the north, five in the central region, 27 in the northeast, nine in the east, 12 in the west, and three in the south. Despite these localized concerns, the National Water Resources Office confirmed that overall water supply remains sufficient for continued use through the end of the 2569–2570 dry season.
