"Meteorological Department" issued the fourth bulletin warning of heavy to very heavy rain in upper Thailand. Check which provinces will be affected.
On 17 August 2026, the Meteorological Department website issued Bulletin No. 4 regarding heavy to very heavy rain over upper Thailand, effective 18-21 August 2026. It states that during 18-21 August, Thailand will experience heavy to very heavy rain in some areas, especially in the northern and northeastern regions. This is due to a monsoon trough crossing the north and upper northeast, combined with a fairly strong southwest monsoon covering the Andaman Sea, Thailand, and the Gulf of Thailand.
Residents in these areas are advised to be cautious of dangers from heavy to very heavy rain and accumulated rainfall, which may cause flash floods and landslides. Those living in foothill areas near waterways and low-lying zones should avoid traveling through frequently flooded routes, as temporary flooding may occur.
The upper Andaman Sea will experience fairly strong winds from 19-21 August 2026, with waves 2-3 meters high. Areas with thunderstorms may see waves over 3 meters. The lower Andaman Sea and upper Gulf of Thailand will have waves around 2 meters, rising above 2 meters in thunderstorm zones. Mariners in the Andaman Sea and Gulf of Thailand should navigate with caution and avoid sailing in stormy conditions. Small boats in the upper Andaman Sea are advised to stay ashore during this period.
For safety and to minimize potential impacts, the public should carefully plan their activities and travel during this time. They are urged to follow updates from the Meteorological Department, accessible via www.tmd.go.th or by calling 0-2399-4012-13 and 1182, available 24 hours.
18 August 2026
19 August 2026
20 August 2026
21 August 2026
