The Meteorological Department issued its 18th announcement warning of "heavy to very heavy rain" Check which provinces may face flash floods and mountain runoff.
21 May 2026 GMT+7The Meteorological Department's websiteissued a statement titled "Heavy to very heavy rain over Thailand and strong winds in the Andaman Sea" The 18th announcement (effective until 21 May 2026) states that rainfall in Thailand is beginning to decrease but heavy rain persists in some areas, mostly in the west, the east, and the upper northeastern region, with some very heavy rain in parts of the western southern region.
This is due to a relatively strong southwest monsoon covering the upper Andaman Sea and a weakening Thailand monsoon, combined with a low-pressure area over northern Thailand and northern Vietnam. Residents in these areas are advised to be cautious of heavy to very heavy rainfall and accumulated rain that could cause flash floods and mountain runoff, especially in foothill areas near waterways and low-lying basins.
Waves and winds in the Andaman Sea and Gulf of Thailand are quite strong. In the upper Andaman Sea, from Phuket northward, waves reach 2–3 meters high, with waves over 3 meters in areas with thunderstorms.
In the lower Andaman Sea, from Krabi southward, and in the upper Gulf of Thailand, waves are about 2 meters high, with waves exceeding 2 meters where thunderstorms occur. Mariners in these areas are advised to navigate cautiously and avoid sailing in areas with thunderstorms. Small boats in the upper Andaman Sea are advised to stay ashore during this period.
The public is urged to follow announcements from the Meteorological Department and can check updates on the department's website http://www.tmd.go.th or call 0-2399-4012-13 and 1182 24 hours a day. This announcement is the final one regarding this event.
21 May 2026 GMT+7
Thanks to the Meteorological Department website