Thailand Issues Heavy Rain and Flash Flood Warning for 55 Provinces

The Thai Meteorological Department (TMD) released its eighth announcement on September 18, 2026, warning of heavy to very heavy rainfall across 55 provinces. This weather event, effective from September 18 to 20, is driven by a cold air mass from China interacting with a monsoon trough and a strong southwest monsoon over the Andaman Sea and the Gulf of Thailand.

Residents and travelers in affected areas, particularly those near foothills and low-lying regions, are advised to exercise caution regarding flash floods and forest runoff. The TMD specifically warns against traveling through areas prone to recurring flooding, as short-term water accumulation is expected. Furthermore, maritime conditions in the Andaman Sea are currently hazardous, with wave heights reaching 2 to 3 meters, and exceeding 3 meters in areas experiencing thunderstorms. Mariners in both the Gulf of Thailand and the Andaman Sea are urged to proceed with extreme caution.

While the TMD has provided a clear timeline for the weather system, the specific intensity of rainfall in localized areas remains subject to change. Residents and visitors are encouraged to monitor official updates from the Thai Meteorological Department and local authorities for real-time developments and specific evacuation or safety instructions as the situation evolves.