The Meteorological Department's first announcement warns to prepare for unstable weather from 24–28 October 2026. The southern region will experience heavy to very heavy rain, risking flash floods and forest runoff, while northern Thailand will have rain followed by a temperature drop caused by a cold air mass from China.
At 17:00 on 23 October 2026, the Meteorological Department issued Announcement No. 1 regarding heavy to very heavy rain in the southern region and unstable weather in northern Thailand, affecting 24–28 October 2026. During this period, the southern region will have continuous rain with heavy rainfall in many areas and very heavy rain in some places. The public is urged to beware of dangers from accumulated rain, which may cause flash floods and forest runoff, especially in foothill areas near waterways and low-lying areas where flooding may occur.
From 25–27 October 2026, northern Thailand will experience unstable weather characterized by thunderstorms, strong gusty winds, and heavy rain in some areas. The northeastern region will be affected first, followed by the northern, central regions, including Bangkok and its vicinity, and the eastern region. The public should be cautious of thunderstorms, strong winds, and avoid staying in open areas, under large trees, and unstable billboards.
This is due to a high-pressure system or cold air mass from China spreading over northern Thailand and the South China Sea, causing easterly winds over Thailand and the Gulf of Thailand. Meanwhile, the monsoon trough passing through the southern region will strengthen.
Waves and winds in the Andaman Sea and the Gulf of Thailand, especially in areas with thunderstorms, will have wave heights exceeding 2 meters. Mariners in these seas should navigate with caution and avoid sailing in stormy areas.
For safety and to reduce possible impacts, the public is advised to plan their activities and travel carefully during this period. They should continuously follow announcements from the Meteorological Department, accessible via their website at http://www.tmd.go.th or by calling 0-2399-4012-13 and 1182, available 24 hours.