Thailand Issues Heavy Rain and Flash Flood Warning for 65 Provinces

On September 18, 2026, the Thai Meteorological Department (TMD) issued a significant weather warning affecting 65 provinces across Thailand. According to the report by Khaosod Online, the country is experiencing heavy to very heavy rainfall, covering approximately 70% of these areas, including Bangkok and its surrounding metropolitan region.

This weather pattern is driven by a monsoon trough passing through the lower North, upper Central, and Northeast regions, combined with a strong southwest monsoon over the Andaman Sea and the Gulf of Thailand. Residents and travelers are advised to exercise extreme caution regarding potential flash floods, forest runoff, and landslides, particularly in low-lying areas and regions near mountain slopes.

Marine conditions are also hazardous. The upper Andaman Sea is experiencing waves between 2 and 3 meters, with heights exceeding 3 meters in thunderstorm areas. The lower Andaman Sea and upper Gulf of Thailand face waves of approximately 2 meters. Consequently, small boats in the upper Andaman Sea are advised to remain ashore until September 20, 2026. All mariners are urged to navigate with caution and avoid areas experiencing thunderstorms. While the TMD has provided this 24-hour forecast, individuals should monitor local updates for specific provincial developments and potential changes in weather intensity as the monsoon conditions evolve.