TMD flags very heavy rain in Northeast and flash-flood risk

The Thai Meteorological Department (TMD) has warned of heavy rain across parts of upper Thailand through September 7, with very heavy downpours in the eastern Northeast raising the risk of flash floods and rapid run-off.

Advisory No 8, issued at 5pm on Saturday (September 5, 2026), covers September 5–7.

A monsoon trough across the North and upper Northeast, combined with a moderate southwest monsoon over the Andaman Sea, Thailand and the Gulf of Thailand, is driving the wet weather.

The department urged particular caution in communities along the Mekong River basin, foothills near waterways and low-lying areas, where heavy and accumulated rainfall could trigger flooding.

Residents should avoid routes repeatedly affected by flooding, particularly low-lying roads where temporary inundation may develop, and plan daily activities and journeys carefully.

The latest advisory follows the department’s earlier warning of heavy rain and flash-flood risks through September 7.

Regional forecast

The following forecast is valid from 6pm on September 5 to 6pm on September 6, 2026.

North

• Thunderstorms across 70% of the region, with isolated heavy rain in Mae Hong Son, Chiang Mai, Lampang, Phrae, Nan, Uttaradit, Sukhothai, Tak, Phichit, Phitsanulok and Phetchabun.
• Minimum temperatures of 22–27°C and maximum temperatures of 31–37°C.
• Variable winds at 10–20km/h.

Northeast

• Thunderstorms across 70% of the region.
• Isolated heavy rain in Loei, Nong Khai, Bueng Kan, Nong Bua Lamphu, Udon Thani, Sakon Nakhon, Nakhon Phanom, Khon Kaen, Kalasin, Mukdahan, Maha Sarakham, Roi Et, Yasothon and Surin.
• Isolated very heavy rain in Si Sa Ket, Amnat Charoen and Ubon Ratchathani.
• Minimum temperatures of 23–26°C and maximum temperatures of 30–35°C.
• Southwesterly winds at 10–20km/h.

Central region

• Thunderstorms across 60% of the region, with isolated heavy rain in Saraburi, Kanchanaburi, Ratchaburi, Nakhon Pathom and Samut Sakhon.
• Minimum temperatures of 23–26°C and maximum temperatures of 34–37°C.
• Southwesterly winds at 10–20km/h.

East

• Thunderstorms across 60% of the region, with isolated heavy rain in Nakhon Nayok, Prachin Buri, Sa Kaeo, Chachoengsao, Chanthaburi and Trat.
• Minimum temperatures of 24–28°C and maximum temperatures of 31–35°C.
• Southwesterly winds at 15–35km/h.
• Waves of 1–2 metres, rising above 2 metres during thunderstorms.

South, east coast

• Thunderstorms across 30% of the region, mainly in Phetchaburi, Prachuap Khiri Khan, Chumphon, Surat Thani, Yala and Narathiwat.
• Minimum temperatures of 23–26°C and maximum temperatures of 33–36°C.
• Southwesterly winds at 15–35km/h.
• Waves of about 1 metre, reaching 1–2 metres offshore and exceeding 2 metres during thunderstorms.

South, west coast

• Thunderstorms across 40% of the region, mainly in Ranong, Phang Nga, Trang and Satun.
• Minimum temperatures of 24–27°C and maximum temperatures of 31–35°C.
• From Phuket northwards, southwesterly winds at 20–35km/h, with waves of about 2 metres, rising above 2 metres during thunderstorms.
• From Krabi southwards, southwesterly winds at 15–35km/h, with waves of 1–2 metres, rising above 2 metres during thunderstorms.

Bangkok and surrounding provinces

• Thunderstorms across 60% of the area, with isolated heavy rain.
• Minimum temperatures of 26–28°C and maximum temperatures of 34–36°C.
• Southwesterly winds at 10–20km/h.

Weather updates

The public is advised to follow further TMD announcements. Information is available around the clock through:

• Website: www.tmd.go.th.
• Telephone: 02-399-4012–13.
• Weather hotline: 1182.