Severe Weather Alert: 38 Provinces Face Heavy Rain and Flood Risk

Thailand's Meteorological Department has issued a weather alert for 38 provinces, warning of continuous heavy rain affecting 70 percent of areas with risks of flash floods and overflow. Bangkok and surrounding areas are also included. As of August 21, 2025, the department forecasts heavy to very heavy rain in the northern and upper northeastern regions, with heavy rain in central and eastern Thailand including Bangkok and its vicinity over the next 24 hours.

A monsoon trough is passing through the northern and upper northeastern regions, combined with strong southwest monsoon winds over the Andaman Sea and Gulf of Thailand. Residents in affected areas are urged to be cautious of heavy to very heavy rainfall and accumulated water, which may cause flash flooding, flash floods, and riverbank overflow, especially in foothill and low-lying areas.

Wave heights in the upper Andaman Sea and upper Gulf of Thailand are expected to reach 2-3 meters, exceeding 3 meters during thunderstorms. The lower Andaman Sea will see waves around 2 meters, over 2 meters during thunderstorms. Fishing boats in both areas are advised to navigate carefully and avoid thunderstorm zones, with small boats in the upper regions advised to stay ashore.

For the 24-hour forecast from 6:00 a.m. today to 6:00 a.m. tomorrow:

Northern Region: Thunderstorms in 80 percent of areas with heavy rain in some areas, particularly in Mae Hong Son, Chiang Mai, Chiang Rai, Lampun, Phayao, Nan, and Phrae provinces. Very heavy rain expected in Lampang, Kamphaeng Phet, Uttaradit, Sukhothai, Tak, Phitsanulok, Phichit, and Phetchabun. Minimum temperature 23-26°C, maximum 27-32°C. Southwest wind 10-20 km/h.

Northeastern Region: Thunderstorms in 80 percent of areas with heavy rain in some areas, particularly in Bueng Kan, Sakon Nakhon, Nakhon Phanom, Chaiyaphum, and Khon Kaen. Very heavy rain expected in Loei, Nong Khai, Nong Bua Lamphu, and Udon Thani. Minimum temperature 22-25°C, maximum 26-30°C. Southwest wind 10-20 km/h.

Central Region: Thunderstorms in 70 percent of areas with heavy rain in some areas, particularly in Nakhon Sawan, Uthai Thani, Kanchanaburi, and Ratchaburi. Minimum temperature 23-25°C, maximum 28-33°C. Southwest wind 10-25 km/h.

Eastern Region: Thunderstorms in 70 percent of areas with heavy rain in some areas, particularly in Nakhon Nayok, Prachuap Khiri Khan, Chanthaburi, and Trat. Minimum temperature 23-28°C, maximum 29-33°C. Southwest wind 20-40 km/h. Sea waves 2-3 meters, exceeding 3 meters during thunderstorms.

Southern Region (Eastern Coast): Thunderstorms in 40 percent of areas, mainly in Phetchaburi, Prachuap Khiri Khan, and Chumphon. Minimum temperature 23-26°C, maximum 29-36°C. From Surat Thani northward: Southwest wind 15-35 km/h, waves 1-2 meters nearshore, exceeding 2 meters during thunderstorms. From Nakhon Si Thammarat southward: Southwest wind 15-35 km/h, waves around 1 meter nearshore, 1-2 meters offshore, exceeding 2 meters during thunderstorms.