TMD forecasts 70% rain in Thailand’s North, Northeast and Bangkok

The Thai Meteorological Department (TMD) said in an announcement issued at 5pm on Wednesday (September 16, 2026) that isolated heavy to very heavy rain was expected across Thailand from September 17 through 20.

The North and Northeast were expected to be affected first on Thursday, followed by the central, eastern and southern regions on Friday.

The department said a high-pressure system or cool air mass from China would extend over the upper North and upper Northeast, causing the monsoon trough to shift southwards across the lower Central region, the East and the upper South.

At the same time, the southwest monsoon prevailing over the Andaman Sea, Thailand and the Gulf of Thailand would strengthen.

“People across Thailand are advised to be alert to dangers from heavy to very heavy rain and accumulated rainfall, which may cause flash floods and rapid run-off from forested areas, particularly on foothill slopes near waterways and in low-lying areas.

Travel on routes prone to repeated flooding should be avoided, especially in low-lying areas where short-term waterlogging may occur.”

Conditions in the Andaman Sea will be fairly rough, with waves reaching 2-3 metres and exceeding 3 metres during thunderstorms.

Mariners in the Gulf of Thailand and the Andaman Sea should proceed with caution and avoid areas affected by thunderstorms.

Small boats in the Andaman Sea should remain ashore from September 17 through 20.

TMD forecast for Thailand from 6pm on Wednesday (September 16) to 6pm on Thursday (September 17)

Northern region

• Thundershowers across 70% of the region, with isolated heavy rain in Mae Hong Son, Chiang Mai, Chiang Rai, Lamphun, Uttaradit, Tak, Phitsanulok, Phichit and Phetchabun.
• Isolated very heavy rain in Lampang, Phayao, Nan and Phrae.
• Minimum temperatures of 22-26°C and maximum temperatures of 30-36°C.
• Variable winds at 10-20 kilometres per hour.

Northeastern region

• Thundershowers across 70% of the region, with isolated heavy rain in Loei, Nong Bua Lamphu, Bueng Kan, Udon Thani, Sakon Nakhon, Nakhon Phanom, Chaiyaphum, Khon Kaen, Kalasin, Mukdahan, Maha Sarakham, Yasothon, Amnat Charoen and Ubon Ratchathani.
• Isolated very heavy rain in Nong Khai.
• Minimum temperatures of 22-25°C and maximum temperatures of 31-35°C.
• Southwesterly winds at 10-20 kilometres per hour.

Central region

• Thundershowers across 60% of the region, with isolated heavy rain in Nakhon Sawan, Sing Buri, Lop Buri, Saraburi, Kanchanaburi, Ratchaburi, Nakhon Pathom and Samut Sakhon.
• Minimum temperatures of 23-25°C and maximum temperatures of 33-36°C.
• Southwesterly winds at 10-20 kilometres per hour.

Eastern region

• Thundershowers across 60% of the region, with isolated heavy rain in Nakhon Nayok, Prachin Buri, Chachoengsao, Chanthaburi and Trat.
• Minimum temperatures of 23-27°C and maximum temperatures of 32-34°C.
• Southwesterly winds at 15-35 kilometres per hour.
• Waves of 1-2 metres, exceeding 2 metres during thunderstorms.

Southern region, east coast

• Thundershowers across 60% of the region, with isolated heavy rain in Prachuap Khiri Khan, Chumphon, Surat Thani, Yala and Narathiwat.
• Minimum temperatures of 21-24°C and maximum temperatures of 33-35°C.
• Southwesterly winds at 15-35 kilometres per hour.
• Waves of about 1 metre, reaching 1-2 metres offshore and more than 2 metres during thunderstorms.

Southern region, west coast

• Thundershowers across 70% of the region, with isolated heavy rain in Ranong, Phang Nga and Satun.
• Minimum temperatures of 23-26°C and maximum temperatures of 30-35°C.
• Southwesterly winds at 15-35 kilometres per hour.
• Waves of 1-2 metres, exceeding 2 metres during thunderstorms.

Bangkok and surrounding areas

• Thundershowers across 70% of the area, with isolated heavy rain.
• Minimum temperatures of 24-26°C and maximum temperatures of 33-35°C.
• Southwesterly winds at 10-20 kilometres per hour.