The Thai Meteorological Department forecasts heavy rain in 65 provinces today, 18 September 2026. Bangkok can expect fairly widespread showers and isolated heavy rain, with lows and highs of 24-35°C. Very heavy rain is possible in Phetchabun, Phitsanulok, Uttaradit, Chaiyaphum, Khon Kaen, Loei, Nakhon Ratchasima, Nong Bua Lamphu, Chanthaburi, Nakhon Nayok, Prachin Buri, Trat, Chumphon, Surat Thani, Phang Nga, Phuket, Ranong.
The monsoon trough move up to lying across the lower North, the central region and the Northeast of Thailand while the rather strong southwest monsoon prevailing over the Andaman Sea, Thailand and the Gulf. Isolated heavy rains are forecast in the country while isolated very heavy rain are possible in the North, the Northeast, the East and the South (west coast) regions.
Bangkok
Fairly widespread thundershowers and isolated heavy rain. Minimum temperature 24-26°C. Maximum temperature 32-35°C. Southwesterly winds 10-25 km/h.
North
Fairly widespread thundershowers and isolated heavy rain in Chiang Mai, Chiang Rai, Lampang, Phayao, Nan, Phrae, Tak, Sukhothai, Kamphaeng Phet, and Phichit. Isolated very heavy rain in Uttaradit, Phitsanulok, and Phetchabun. Minimum temperature 22-27°C. Maximum temperature 30-36°C. Variable winds 10-20 km/h.
Northeast
Fairly widespread thundershowers and isolated heavy rain in Nong Khai, Bueng Kan, Udon Thani, Sakon Nakhon, Nakhon Phanom, Kalasin, Mukdahan, Maha Sarakham, Roi Et, Yasothon, Amnat Charoen, Buriram, Surin, Si Sa Ket, and Ubon Ratchathani. Isolated very heavy rain in Loei, Nong Bua Lamphu, Chaiyaphum, Khon Kaen, and Nakhon Ratchasima. Minimum temperature 22-25°C. Maximum temperature 29-34°C. Variable winds 10-20 km/h.
Central
Fairly widespread thundershowers and isolated heavy rain in Nakhon Sawan, Uthai Thani, Chai Nat, Lop Buri, Saraburi, Sing Buri, Ang Thong, Phra Nakhon Si Ayutthaya, Suphan Buri, Kanchanaburi, Ratchaburi, Nakhon Pathom, Samut Songkhram, and Samut Sakhon. Minimum temperature 23-25°C. Maximum temperature 33-35°C. Southwesterly winds 10-25 km/h.
East
Fairly widespread thundershowers and isolated heavy rain in Sa Kaeo, Chachoengsao, Chonburi, and Rayong. Isolated very heavy rain in Nakhon Nayok, Prachin Buri, Chanthaburi, and Trat. Minimum temperature 23-27°C. Maximum temperature 30-34°C. Southwesterly winds 20-35 km/h. Wave height about 2 meters and above 2 meters in thundershowers.
South (east coast)
Scattered thundershowers and isolated heavy rain in Phetchaburi, Prachuap Khiri Khan, Nakhon Si Thammarat, and Songkhla. Isolated very heavy rain in Chumphon and Surat Thani. Minimum temperature 22-25°C. Maximum temperature 31-35°C. From Surat Thani upward: southwesterly winds 20-35 km/h. Wave height 1-2 meters, about 2 meters offshore and above 2 meters in thundershowers. From Nakhon si Thammarat downward: southwesterly winds 15-35 km/h. Wave height about 1 meter, 1-2 meters offshore and above 2 meters in thundershowers.
South (west coast)
Fairly widespread thundershowers and isolated heavy rain in Krabi, Trang, and Satun. Isolated very heavy rain in Ranong, Phang Nga, and Phuket. Minimum temperature 23-26°C. Maximum temperature 28-34°C. From Phuket upward: southwesterly winds 20-40 km/h. Wave height 2-3 meters and above 3 meters in thundershowers. From Krabi downward: southwesterly winds 20-35 km/h. Wave height about 2 meters and above 2 meters in thundershowers.
Warnings
People should beware of heavy to very heavy rains and accumulation that may cause flash floods, overflows and landslides especially along the waterways near foothills and lowlands.
Source: Thai Meteorological Department daily forecast, announcement of 18 September 2026.
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