Safety
Thai Meteorological Department Issues Heavy Rain Warning for August 18–21
Thailand's weather bureau has issued a severe weather alert for the northern and northeastern regions, warning of potential flash floods and strong coastal waves.
The Thai Meteorological Department (TMD) has released its fifth announcement regarding heavy to very heavy rainfall expected across upper Thailand from August 18 to August 21, 2026. According to Khaosod Online, this weather pattern is driven by a monsoon trough passing through the northern and upper northeastern regions, combined with a strengthening southwest monsoon over the Andaman Sea and the Gulf of Thailand.
Residents and travelers in these areas are advised to exercise caution due to the risk of flash floods and forest runoff, particularly in low-lying areas and regions near mountain slopes. The TMD specifically warns of potential hazards from accumulated rainfall and advises against traveling through routes prone to recurring flooding.
Marine conditions are also expected to deteriorate. From August 19 to 21, the upper Andaman Sea will experience waves between 2 and 3 meters, with heights exceeding 3 meters in thunderstorm areas. The lower Andaman Sea and upper Gulf of Thailand are expected to see waves of approximately 2 meters, rising higher during storms. Mariners are urged to navigate with extreme caution and avoid areas experiencing thunderstorms. Small vessels in the upper Andaman Sea are advised to monitor conditions closely. As this is a developing weather event, individuals should continue to monitor official updates from the TMD for specific provincial impacts and potential changes to the forecast.