Monsoon rains raise flood risk across upper Thailand under TMD alert

The Thai Meteorological Department (TMD) has warned of heavy to very heavy rain in parts of upper Thailand until Monday (September 7, 2026).

Isolated heavy rain is forecast across upper Thailand on September 6 and 7, with isolated very heavy rain in the eastern part of the Northeast.

A monsoon trough lies across the North and upper Northeast, while a moderate southwest monsoon prevails over the Andaman Sea, Thailand and the Gulf of Thailand.

People in the affected areas are advised to remain alert to hazards from heavy to very heavy rain and accumulated rainfall, which could cause flash floods and rapid run-off.

Particular caution is advised in the Mekong River Basin, foothill areas near waterways and low-lying areas.

People should avoid routes prone to repeated flooding, especially in low-lying areas where temporary flooding may occur.

Northern region

• Thunderstorms are forecast across 70% of the region, with isolated heavy rain in Mae Hong Son, Chiang Mai, Lampang, Nan, Phrae, Uttaradit, Sukhothai, Tak, Phichit, Phitsanulok and Phetchabun.
• Minimum temperatures will range from 22 to 27 degrees Celsius and maximum temperatures from 32 to 37 degrees Celsius.
• Variable winds will blow at 10–20 kilometres per hour.

Northeastern region

• Thunderstorms are forecast across 70% of the region, with isolated heavy rain in Loei, Nong Khai, Bueng Kan, Udon Thani, Sakon Nakhon, Nakhon Phanom, Khon Kaen, Kalasin, Mukdahan, Maha Sarakham, Roi Et, Yasothon, Amnat Charoen, Surin and Si Sa Ket. Isolated very heavy rain is forecast in parts of Ubon Ratchathani.
• Minimum temperatures will range from 23 to 26 degrees Celsius and maximum temperatures from 31 to 35 degrees Celsius.
• Southwesterly winds will blow at 10–20 kilometres per hour.

Central region

• Thunderstorms are forecast across 60% of the region, with isolated heavy rain in Lop Buri, Saraburi, Phra Nakhon Si Ayutthaya, Kanchanaburi, Ratchaburi, Nakhon Pathom and Samut Sakhon.
• Minimum temperatures will range from 23 to 26 degrees Celsius and maximum temperatures from 35 to 37 degrees Celsius.
• Southwesterly winds will blow at 10–20 kilometres per hour.

Eastern region

• Thunderstorms are forecast across 60% of the region, with isolated heavy rain in Nakhon Nayok, Prachin Buri, Chachoengsao, Chanthaburi and Trat.
• Minimum temperatures will range from 24 to 28 degrees Celsius and maximum temperatures from 32 to 35 degrees Celsius.
• Southwesterly winds will blow at 15–35 kilometres per hour. Waves will be 1–2 metres high and exceed 2 metres in areas experiencing thunderstorms.

Southern region (east coast)

• Thunderstorms are forecast across 30% of the region, mainly in Phetchaburi, Prachuap Khiri Khan, Chumphon, Surat Thani and Narathiwat.
• Minimum temperatures will range from 23 to 26 degrees Celsius and maximum temperatures from 34 to 36 degrees Celsius.
• Southwesterly winds will blow at 15–35 kilometres per hour. Waves will be about 1 metre high. Offshore waves will be 1–2 metres high, while waves in areas experiencing thunderstorms will exceed 2 metres.

Southern region (west coast)

• Thunderstorms are forecast across 40% of the region, mainly in Ranong, Phang Nga, Trang and Satun.
• Minimum temperatures will range from 24 to 27 degrees Celsius and maximum temperatures from 31 to 34 degrees Celsius.
• From Phuket northwards, southwesterly winds will blow at 20–35 kilometres per hour. Waves will be about 2 metres high and exceed 2 metres in areas experiencing thunderstorms.
• From Krabi southwards, southwesterly winds will blow at 15–35 kilometres per hour. Waves will be 1–2 metres high and exceed 2 metres in areas experiencing thunderstorms.

Bangkok and surrounding areas

• Thunderstorms are forecast across 60% of the area, with isolated heavy rain.
• Minimum temperatures will range from 26 to 28 degrees Celsius and maximum temperatures from 34 to 36 degrees Celsius.
• Southwesterly winds will blow at 10–20 kilometres per hour.