Meteorological Bulletin No. 11 warns of heavy rain in some areas across Thailand, with increased rainfall in the South. The alert is effective until 13 Sep 2026. Residents in foothill and low-lying areas are advised to be cautious of flooding and flash floods due to heavy rain.
At 05:00 on 12 September 2026, the Meteorological Department issued Bulletin No. 11 regarding heavy to very heavy rainfall in Thailand, effective until 13 September 2026. Between 12 and 13 September 2026, the South will see increased rainfall with some areas experiencing heavy to very heavy rain. Meanwhile, the lower North, Northeast, Central regions, including Bangkok and its vicinity, and the East will experience heavy rain in some locations.
This situation is due to a high-pressure system or cold air mass from China extending over the upper North and upper Northeast. At the same time, the monsoon trough extends across the lower Central, upper South, upper Gulf of Thailand, and the East into a strong low-pressure area near the central coast of Vietnam. Additionally, the southwest monsoon covering the Andaman Sea, the South, and the Gulf of Thailand will strengthen.
The public is advised to be alert to the dangers posed by heavy to very heavy rainfall and accumulation that may cause flash floods and sudden water runoff. Those in foothill areas near waterways and low-lying zones should avoid traveling through frequently flooded routes, especially lowland areas prone to short-term waterlogging.
Furthermore, the strong low-pressure area near the central coast of Vietnam is expected to intensify into a tropical cyclone and is forecasted to approach northern Vietnam between 13 and 14 September 2026. The public should continuously monitor weather updates during this period.
For safety and to minimize potential impacts, the public is advised to plan their activities and travel during this period with caution. Please stay updated with announcements from the Meteorological Department, accessible at http://www.tmd.go.th or via phone at 0-2399-4012-13 and 1182, available 24 hours.
Northern region: Thunderstorms in 40% of the area, mainly in Mae Hong Son, Chiang Mai, Tak, Phichit, Kamphaeng Phet, and Phetchabun provinces. Minimum temperatures 21-26°C, maximum 31-36°C. East winds at 10-20 km/h.
Northeastern region: Thunderstorms in 40% of the area with heavy rain in some parts, especially Ubon Ratchathani province. Minimum temperatures 21-24°C, maximum 33-34°C. Northeast winds at 10-20 km/h.
Central region: Thunderstorms in 70% of the area with heavy rain in some parts, including Nakhon Sawan, Uthai Thani, Chai Nat, Phra Nakhon Si Ayutthaya, Suphan Buri, Kanchanaburi, Ratchaburi, Nakhon Pathom, Samut Sakhon, and Samut Songkhram provinces. Minimum temperatures 23-25°C, maximum 33-35°C. North winds at 10-20 km/h.
Eastern region: Thunderstorms in 70% of the area with heavy rain in some parts, including Nakhon Nayok, Prachinburi, Sa Kaeo, Chachoengsao, Chonburi, Rayong, Chanthaburi, and Trat provinces. Minimum temperatures 23-25°C, maximum 31-34°C. Variable winds at 15-35 km/h. Sea waves 1-2 meters high; over 3 meters where thunderstorms occur.
Southern region (East Coast): Thunderstorms in 70% of the area with heavy rain in some areas of Phetchaburi, Surat Thani, Nakhon Si Thammarat, and Phatthalung provinces; very heavy rain in parts of Prachuap Khiri Khan and Chumphon. Minimum temperatures 22-24°C, maximum 31-33°C. From Surat Thani northwards: West winds at 15-35 km/h, sea waves 1-2 meters high; over 2 meters where thunderstorms occur. From Nakhon Si Thammarat southwards: Northwest winds at 15-35 km/h, sea waves about 1 meter high nearshore and 1-2 meters offshore; over 2 meters where thunderstorms occur.
Southern region (West Coast): Thunderstorms in 70% of the area with heavy rain in parts of Phuket, Krabi, Trang, and Satun; very heavy rain in parts of Ranong and Phang Nga. Minimum temperatures 23-25°C, maximum 29-32°C. From Phuket northwards: West winds at 20-35 km/h, sea waves about 2 meters high; over 2 meters where thunderstorms occur. From Krabi southwards: Northwest winds at 15-35 km/h, sea waves 1-2 meters high; over 2 meters where thunderstorms occur.
Bangkok and vicinity: Thunderstorms in 70% of the area with heavy rain in some locations. Minimum temperatures 24-25°C, maximum 33-34°C. Northwest winds at 10-20 km/h.