The Meteorological Department issued Bulletin 11, warning of heavy to very heavy rain in Thailand and listing provinces affected by flash floods and flash floods.
On 18 May 2026, the Meteorological Department issued Bulletin 11 regarding heavy to very heavy rain over Thailand and strong waves in the Andaman Sea (effective until 18 May 2026).
It stated that upper Thailand will experience some heavy rain, mostly in the western areas and upper northeastern region, with heavy to very heavy rain in some parts of the western South and East. Residents in these areas are advised to be cautious of heavy to very heavy rain and accumulated rainfall, which may cause flash floods and flash floods, especially in foothill areas near water flow paths and low-lying areas. This is due to a fairly strong southwest monsoon covering the Andaman Sea, Thailand, and the Gulf of Thailand. People should also take care of their health during these weather changes.
Waves and winds in the Andaman Sea and Gulf of Thailand are fairly strong. In the upper Andaman Sea, from Phuket province northward, waves reach 2–3 meters high, with waves exceeding 3 meters in thunderstorms. In the lower Andaman Sea, from Krabi province southward, and in the upper Gulf of Thailand, waves reach about 2 meters, with waves exceeding 2 meters in thunderstorms. Fishermen in these areas are urged to navigate cautiously and avoid sailing in thunderstorms. Small boats in the upper Andaman Sea should remain ashore.
From 19 to 22 May 2026, rainfall in Thailand is expected to increase, with heavy to very heavy rain in some areas, mostly in the western part of the country, the North, upper Northeast, East, and the western South. This is due to a low-pressure area over the Mergui Archipelago in Myanmar that is likely to strengthen, combined with a fairly strong southwest monsoon covering the Andaman Sea, Thailand, and the Gulf of Thailand.
As of 14 May 2026,
The public is urged to follow announcements from the Meteorological Department and can access information on the Meteorological Department's website.http://www.tmd.go.thor by calling 0-2399-4012-13 and 1182, available 24 hours a day.
Announcement issued on 18 May 2026 at 05:00 GMT+7.
The Meteorological Department will issue the next bulletin on 18 May 2026 at 17:00 GMT+7.