Thailand is bracing for significant rainfall on September 17th, with the Thai Meteorological Department issuing heavy rain warnings for 57 provinces. The northern, northeastern, and western coastal regions of the south are expected to experience the most intense downpours. Residents in vulnerable areas are advised to be vigilant for potential flash floods, overflows, and landslides.
Nationwide Weather Outlook
A monsoon trough stretching across the northern and northeastern parts of the country, combined with a strengthening southwest monsoon over the Andaman Sea, Thailand, and the Gulf, is driving the widespread precipitation. The meteorological department has specifically highlighted the risk of very heavy rain in several provinces, including Nan, Phrae, Uttaradit, Loei, Nong Khai, Phang Nga, and Ranong.
The department is urging caution for communities situated near waterways, foothills, and low-lying areas, as these regions are most susceptible to the adverse effects of heavy rainfall, such as flash floods and landslides.
Regional Forecasts and Warnings
Bangkok and Vicinity
The capital city, Bangkok, is forecast to experience fairly widespread thundershowers with isolated instances of heavy rain. Temperatures are expected to range from a low of 24-26°C to a high of 33-35°C, with southwesterly winds blowing at 10 to 25 km/h.
Northern Thailand
Northern provinces, including Chiang Mai, Chiang Rai, Lamphun, Lampang, Phayao, and Sukhothai, will also see fairly widespread thundershowers and isolated heavy rain. Kamphaeng Phet, Phichit, Phitsanulok, and Phetchabun are also anticipating heavy rainfall. The risk of very heavy rain is particularly noted for Nan, Phrae, and Uttaradit. Daytime temperatures will range from 30-36°C, with lows between 22-27°C. Winds will be variable, ranging from 10 to 20 km/h.
Northeastern Thailand
The Northeast region faces similar conditions, with fairly widespread thundershowers and isolated heavy rain expected in provinces such as Bueng Kan, Nong Bua Lam Phu, Udon Thani, Sakon Nakhon, Nakhon Phanom, Chaiyaphum, Khon Kaen, and Kalasin. Mukdahan, Maha Sarakham, Roi Et, Yasothon, Amnat Charoen, Nakhon Ratchasima, Buri Ram, and Ubon Ratchathani are also included in the forecast. Very heavy rain is a possibility in Loei and Nong Khai. Temperatures will be between 29-35°C during the day, with overnight lows of 22-25°C. Southwesterly winds are predicted at 10 to 20 km/h.
Central Thailand
Central provinces, including Nakhon Sawan, Chai Nat, Lop Buri, Saraburi, and Phra Nakhon Si Ayutthaya, are set to experience fairly widespread thundershowers with isolated heavy rain. Suphan Buri, Kanchanaburi, Ratchaburi, Nakhon Pathom, Samut Songkhram, and Samut Sakhon will face the same weather patterns. Highs are predicted to reach 33-36°C, with lows of 23-25°C. Southwesterly winds will range from 10 to 25 km/h.
Eastern Thailand
The eastern region, encompassing Nakhon Nayok, Prachin Buri, Chachoengsao, Chon Buri, Rayong, Chanthaburi, and Trat, will also experience fairly widespread thundershowers and isolated heavy rain. Temperatures are expected to be between 31-34°C, with lows of 23-27°C. Southwesterly winds will be stronger here, ranging from 20 to 35 km/h. Sea conditions in the Gulf of Thailand will see waves of about 2 metres, potentially exceeding this height during thundershowers.
Southern Thailand (East Coast)
Along the east coast of the south, scattered thundershowers with isolated heavy rain are forecast for Phetchaburi, Prachuap Khiri Khan, Chumphon, Surat Thani, Nakhon Si Thammarat, and Songkhla. Daytime highs will be between 32-35°C, with lows of 21-24°C. Southwesterly winds will range from 15 to 35 km/h. Waves in the Gulf are expected to be 1-2 metres, rising above 2 metres during thundershowers.
Southern Thailand (West Coast)
The west coast of the south, including Phuket, Krabi, and Trang, will experience fairly widespread thundershowers with isolated heavy rain. Provinces like Ranong and Phang Nga are at risk of very heavy rainfall. Temperatures will range from 28-33°C, with lows of 23-26°C. Southwesterly winds will be strong, between 20 to 40 km/h. In the Andaman Sea, waves are expected to reach 2-3 metres, and could exceed 3 metres in thundershowers from Phuket northward. South of Phuket, waves will be around 2 metres, potentially exceeding this during storms.
Maritime and Flood Warnings
All vessels operating in the Andaman Sea and the Gulf of Thailand are advised to exercise extreme caution and avoid areas experiencing thundershowers. Small boats in the upper Andaman Sea are particularly warned to remain ashore until September 20th, 2026, due to hazardous sea conditions.
The public, especially those residing in flood-prone areas, are urged to stay informed and take necessary precautions against potential flash floods, river overflows, and landslides.
