The Meteorological Department issued Bulletin No. 15 warning of heavy to very heavy rain and listed provinces expected to be affected until 21 May 2026 CE.
On 20 May 2026 CE, the Meteorological Department announced a warning of heavy to very heavy rain across Thailand and strong winds over the Andaman Sea in Bulletin No. 15 (effective through 21 May 2026).
It stated that on 20–21 May 2026 CE, Thailand will experience increased rain with heavy to very heavy showers in some areas, mainly in the western parts of the country, including the northern, upper northeastern, central, eastern, and western southern regions. This is due to a strong southwest monsoon covering the Andaman Sea, Thailand, and the Gulf of Thailand, combined with a low-pressure area near the upper coast of Vietnam.
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, especially in foothill areas near watercourses and low-lying plains.
Winds and waves over the Andaman Sea and Gulf of Thailand are relatively strong. In the upper Andaman Sea from Phuket province northward, waves are 2–3 meters high, with waves exceeding 3 meters in areas with thunderstorms. The lower Andaman Sea from Krabi province southward and the upper Gulf of Thailand have waves about 2 meters high, with waves over 2 meters in thunderstorm areas.
Fishermen in these areas should navigate cautiously and avoid sailing in regions with thunderstorms. Small boats in the upper Andaman Sea are advised not to depart from shore during these days.
On 21 May 2026 CE
The public is urged to follow announcements from the Meteorological Department and can access information on the department's website.http://www.tmd.go.thOr call 0-2399-4012-13 and 1182, available 24 hours.
Announcement made on 20 May 2026 CE at 05:00 GMT+7.
The Meteorological Department will issue the next bulletin on 20 May 2026 CE at 17:00 GMT+7.