Thailand weather warning issued for heavy rain and flooding

The Thai Meteorological Department has issued a warning for heavy to very heavy rainfall across parts of Thailand, effective through August 21, 2026. The weather is driven by a monsoon trough passing through the northern and upper northeastern regions, combined with strong southwest monsoon winds covering the Andaman Sea and the Gulf of Thailand.

Heavy rainfall is expected particularly in the North and Northeast. Residents in these areas are advised to beware of flash floods, forest runoffs, and overflowing banks, especially those living near hillsides or in low-lying areas. In the North, provinces such as Chiang Mai, Chiang Rai, Phayao, Nan, Phrae, and Lampang are at risk of very heavy rain.

In the Northeast, very heavy rain is forecasted for Nong Khai, Bueng Kan, Nakhon Phanom, Sakon Nakhon, Mukdahan, and Kalasin. Other regions, including the Central and Eastern parts of the country, will also experience thunderstorms and heavy rain.

Maritime conditions are also significant. Waves in the upper Andaman Sea and upper Gulf of Thailand are expected to reach 2–3 meters, with waves exceeding 3 meters in areas with thunderstorms. Small boats in the upper Andaman Sea are advised to remain ashore for safety.