Meteorological Bureau Issues Heavy Rain Warning Through August 21

The Thai Meteorological Department issued its first severe weather alert warning of heavy to very heavy rainfall across northern Thailand, with significant impacts expected August 18–21, 2025. Residents are urged to be vigilant against flooding and flash floods. On August 15, the department forecasted continued heavy rainfall in scattered areas, with very heavy rain concentrated in the eastern region due to a monsoon trough passing through Myanmar and upper northern Thailand feeding into a low-pressure zone over northern Vietnam, combined with a strengthening southwest monsoon system covering the Andaman Sea, Thailand, and the Gulf of Thailand. The public should prepare for dangers from heavy and accumulated rainfall that may cause sudden flooding and flash floods, particularly in foothill areas, riverbeds, low-lying zones, and the northeastern region where riverbank overflow is possible. In the upper Andaman Sea, wind and wave conditions will be moderately strong, with waves 2–3 meters high, and over 3 meters in thunderstorm areas. Mariners are advised to navigate with caution and avoid thunderstorm zones; small vessels in the upper Andaman should stay ashore. Regional forecasts for the 24 hours from 06:00 today through 06:00 tomorrow include: Northern region—60% thunderstorm coverage with scattered heavy rainfall, especially in Mae Hong Son, Chiang Mai, Chiang Rai, Phayao, Nan, and Tak provinces; low 23–28°C, high 32–35°C; southwest winds 10–20 kph. Northeastern region—60% thunderstorm coverage with scattered heavy rainfall in Udon Thani, Nong Khai, Bueng Kan, Sakon Nakhon, Nakhon Phanom, Mukdahan, Amnat Charoen, and Ubon Ratchathani; low 24–26°C, high 33–35°C; southwest winds 10–20 kph. Central region—40% thunderstorm coverage with scattered heavy rain in Saraburi and Kanchanaburi; low 25–27°C, high 34–36°C; southwest winds 10–25 kph. Eastern region—60% thunderstorm coverage with scattered heavy rainfall in Nakhon Nayok and Prachuap Khiri Khan, with very heavy rain in some areas of Chanthaburi and Trat; low 25–28°C, high 31–34°C; southwest winds 20–35 kph; sea waves 2 meters, over 2 meters during thunderstorms. Southern region (east coast)—40% thunderstorm coverage mainly in Chumphon, Surat Thani, Nakhon Si Thammarat, Songkhla, Yala, and Narathiwat; low 23–26°C, high 33–35°C; southwest winds 20–35 kph; waves 1–2 meters nearshore, 2 meters offshore, over 2 meters in thunderstorm areas. Southern region (west coast)—60% thunderstorm coverage with scattered heavy rain in Trang and Satun; low 24–28°C, high 32–34°C; from Phang Nga northward southwest winds 20–40 kph with waves 2–3 meters, over 3 meters in thunderstorms; from Phuket southward southwest winds 15–35 kph with waves 1–2 meters, over 2 meters in thunderstorms. Bangkok and vicinity—60% thunderstorm coverage with scattered heavy rainfall; low 26–27°C, high 33°C.