The Meteorological Department's Bulletin No. 13 reports that rainfall in Thailand is beginning to decrease, but some areas in the northern and central regions still experience heavy to very heavy rain. A warning has been issued to beware of flash floods and forest runoff.
21 August 2026 GMT+7Meteorological DepartmentAnnouncement on heavy to very heavy rainfall over upper Thailand (effective until 21 August 2026), Bulletin No. 13 states that rainfall in Thailand is starting to lessen, but heavy to very heavy rain persists in some areas of the northern region and western central region. This is due to the monsoon trough shifting northward across upper northern Thailand and upper Laos into a tropical depression near Hainan Island, China, along with a fairly strong southwest monsoon covering the Andaman Sea, Thailand, and the Gulf of Thailand, which is beginning to weaken.
Residents in the affected areas are urged to be cautious of dangers from heavy to very heavy rain and accumulated rainfall that may cause flash floods and forest runoff, especially in foothill areas near waterways and low-lying zones. Avoid traveling through frequently flooded routes, particularly low-lying areas prone to short-term waterlogging.
Waves over the upper Andaman Sea are quite strong, reaching heights of 2-3 meters; in areas with thunderstorms, waves exceed 3 meters. The upper Gulf of Thailand has waves about 2 meters high, rising above 2 meters where thunderstorms occur. Mariners in the Andaman Sea and Gulf of Thailand should navigate with caution and avoid sailing in thunderstorm areas. Small boats in the upper Andaman Sea are advised to remain ashore during this period.
Meanwhile, a strong low-pressure area near Hainan Island, China, has intensified into a tropical depression and is expected to make landfall in southern Guangdong Province, China, between 23-24 August 2026. This storm will not enter Thailand and thus will not directly affect Thailand's weather. Travelers to the area should monitor weather conditions before departure during these days.
For safety and to minimize potential impacts, the public is advised to plan their activities and travel cautiously during this period. Citizens should follow announcements from the Meteorological Department and can access information on the department’s website.
21 August 2026 GMT+7
Meteorological Departmenthttp://www.tmd.go.thor call 0-2399-4012-13 and hotline 1182, available 24 hours.
Announcement issued on 21 August 2026 at 17:00 GMT+7.
This bulletin from the Meteorological Department is the final update regarding this event.