"Meteorological Department" warning. It warns that some areas in Thailand will experience heavy rain. It lists 13 provinces at risk of heavy to very heavy rainfall and advises residents in those areas to be cautious of dangers from accumulated rain.
26 August 2026 GMT+7Meteorological DepartmentThe 24-hour weather forecast states that Thailand will have heavy rain in some areas of the North, upper Northeast, and East due to a fairly strong southwest monsoon covering the Andaman Sea, Thailand, and the Gulf of Thailand. This combines with a weak monsoon trough crossing upper Myanmar and upper Laos into Tropical Storm Nangka in the Gulf of Tonkin. Residents in these areas are advised to be cautious of heavy and accumulated rainfall.
Northern region: Mae Hong Son, Chiang Rai, Phayao, Nan, and Tak provinces.
Northeastern region: Bueng Kan, Sakon Nakhon, Nakhon Phanom, and Mukdahan provinces.
Eastern region: Nakhon Nayok, Prachinburi, Chanthaburi, and Trat provinces.
The upper Andaman Sea has fairly strong winds with waves 2-3 meters high, and in areas with thunderstorms, waves exceed 3 meters. The upper Gulf of Thailand has waves about 2 meters high, with waves exceeding 2 meters in thunderstorm areas. Mariners in the Andaman Sea and Gulf of Thailand should navigate carefully and avoid traveling in thunderstorm areas. Small boats in the upper Andaman Sea should remain ashore during this period.
Furthermore, "Tropical Storm Nangka" in the Gulf of Tonkin is expected to make landfall in southern Guangxi Province, China today (26 August 2026 GMT+7). This storm will not enter Thailand. People planning to travel in that area should check the weather conditions before traveling during these days.
7-day weather forecast: From 27 to 29 August 2026, northern Thailand will see increased rainfall with heavy rain in some areas of the North, Northeast, and eastern Southern region. Very heavy rain is expected in some western parts of Central, East, and western Southern regions due to a monsoon trough crossing Myanmar and upper Laos into a low-pressure area in northern Vietnam. The fairly strong southwest monsoon continues to cover the Andaman Sea, Thailand, and the Gulf of Thailand.
From 30 August to 1 September 2026, the North and Northeast will experience increased rainfall with heavy to very heavy rain in some areas as the monsoon trough shifts south over the upper North and upper Laos. The fairly strong southwest monsoon will remain over the Andaman Sea, Thailand, and the Gulf of Thailand.
The upper Andaman Sea will have fairly strong winds throughout this period, with waves 2-3 meters high and waves exceeding 3 meters in thunderstorms. The upper Gulf of Thailand will have waves about 2 meters high and over 2 meters in thunderstorms.
Precautions for 27 August to 1 September 2026: Residents in the western parts of the North, upper Northeast, Central, East, and western Southern regions should beware of heavy to very heavy rain and accumulated rainfall, which may cause flash floods, forest runoff, and river overflows, especially near waterways and low-lying areas. Mariners should navigate carefully and avoid traveling in thunderstorm areas. Small boats in the upper Andaman Sea should remain ashore throughout this period.