Bangkok among areas facing very heavy rain on September 24–26

The Thai Meteorological Department (TMD) issued its third warning on Tuesday (September 22), forecasting heavy to very heavy rain across parts of Thailand from September 23–27, 2026, with risks of flash floods and run-off.

The TMD expects the lower Northeast and East to be affected first, followed by other regions. Heavy rain is forecast in many areas of the North, lower Northeast, Central region including Bangkok and surrounding provinces, East and South, with very heavy rain in some places.

A strong low-pressure area near the coast of central Vietnam is expected to move across the lower Northeast, East and Central region, including Bangkok and surrounding provinces, along the monsoon trough extending across upper Thailand, the TMD said. The southwest monsoon over the Andaman Sea, Thailand and the Gulf of Thailand is also forecast to strengthen.

The TMD warned that persistent heavy rain and accumulated rainfall could trigger flash floods and run-off, particularly on foothill slopes near waterways and in low-lying areas. Travellers should avoid routes repeatedly affected by flooding, especially low-lying roads where temporary inundation may occur.

Bangkok faces very heavy rain on September 24–26

Bangkok and surrounding provinces are listed for very heavy rain on September 24–26, with heavy rain expected on September 23 and 27. The daily provincial breakdown distinguishes between areas expected to experience heavy rain and those forecast to receive very heavy rain.

September 23, 2026

Very heavy rain expected

• East: Sa Kaeo, Chanthaburi and Trat.

Heavy rain expected

• Northeast: Chaiyaphum, Nakhon Ratchasima, Buri Ram, Surin, Si Sa Ket and Ubon Ratchathani.
• Central region: Uthai Thani, Chai Nat, Ayutthaya, Suphan Buri, Kanchanaburi, Ratchaburi, Nakhon Pathom and Samut Songkhram, together with Bangkok and surrounding provinces.
• East: Nakhon Nayok, Prachin Buri, Sa Kaeo, Chachoengsao, Chonburi and Rayong.
• South: Phetchaburi, Prachuap Khiri Khan, Chumphon, Surat Thani, Nakhon Si Thammarat, Ranong and Phang Nga.

September 24, 2026

Very heavy rain expected

• Northeast: Nakhon Ratchasima, Buri Ram and Surin.
• Central region: Ang Thong, Ayutthaya, Suphan Buri, Nakhon Pathom and Samut Sakhon, together with Bangkok and surrounding provinces.
• East: Sa Kaeo, Chachoengsao, Chonburi, Rayong, Chanthaburi and Trat.

Heavy rain expected

• North: Tak, Phichit and Phetchabun.
• Northeast: Loei, Nong Bua Lamphu, Udon Thani, Nong Khai, Khon Kaen, Chaiyaphum, Si Sa Ket and Ubon Ratchathani.
• Central region: Nakhon Sawan, Uthai Thani, Chai Nat, Sing Buri, Lop Buri, Saraburi, Kanchanaburi, Ratchaburi and Samut Songkhram.
• East: Nakhon Nayok and Prachin Buri.
• South: Phetchaburi, Prachuap Khiri Khan, Surat Thani, Ranong and Phang Nga.

September 25, 2026

Very heavy rain expected

• North: Tak, Kamphaeng Phet and Phichit.
• Northeast: Nakhon Ratchasima.
• Central region: Nakhon Sawan, Chai Nat, Sing Buri, Ang Thong, Lop Buri, Saraburi, Ayutthaya, Suphan Buri and Kanchanaburi, together with Bangkok and surrounding provinces.
• East: Nakhon Nayok, Prachin Buri, Sa Kaeo, Chachoengsao, Chonburi, Rayong, Chanthaburi and Trat.

Heavy rain expected

• North: Chiang Mai, Lamphun, Lampang, Phrae, Uttaradit, Sukhothai, Phitsanulok and Phetchabun.
• Northeast: Loei, Mukdahan, Kalasin, Khon Kaen, Chaiyaphum, Maha Sarakham, Roi Et, Buri Ram, Surin and Si Sa Ket.
• Central region: Uthai Thani, Ratchaburi, Nakhon Pathom, Samut Sakhon and Samut Songkhram.
• South: Phetchaburi, Prachuap Khiri Khan, Chumphon, Ranong and Phang Nga.

September 26, 2026

Very heavy rain expected

• North: Tak.
• Central region: Nakhon Sawan, Uthai Thani, Saraburi, Ayutthaya, Suphan Buri, Kanchanaburi, Ratchaburi and Nakhon Pathom, together with Bangkok and surrounding provinces.
• East: Sa Kaeo, Chachoengsao, Chonburi, Chanthaburi and Trat.

Heavy rain expected

• North: Kamphaeng Phet, Phichit and Phetchabun.
• Northeast: Khon Kaen, Chaiyaphum, Nakhon Ratchasima and Buri Ram.
• Central region: Chai Nat, Sing Buri, Ang Thong, Lop Buri, Samut Sakhon and Samut Songkhram.
• East: Nakhon Nayok, Prachin Buri and Rayong.
• South: Phetchaburi, Prachuap Khiri Khan, Ranong and Phang Nga.

September 27, 2026

Very heavy rain expected

• Central region: Kanchanaburi and Ratchaburi.
• East: Chanthaburi and Trat.

Heavy rain expected

• North: Tak, Kamphaeng Phet, Phichit and Phetchabun.
• Northeast: Loei, Nong Bua Lamphu, Udon Thani, Nong Khai, Bueng Kan, Sakon Nakhon, Mukdahan, Yasothon, Kalasin, Khon Kaen, Chaiyaphum, Nakhon Ratchasima, Maha Sarakham, Roi Et, Amnat Charoen, Buri Ram, Surin, Si Sa Ket and Ubon Ratchathani.
• Central region: Nakhon Sawan, Uthai Thani, Chai Nat, Sing Buri, Ang Thong, Lop Buri, Saraburi, Ayutthaya, Suphan Buri, Nakhon Pathom, Samut Sakhon and Samut Songkhram, together with Bangkok and surrounding provinces.
• East: Nakhon Nayok, Prachin Buri, Sa Kaeo, Chachoengsao, Chonburi and Rayong.

Small boats in upper Gulf urged to stay ashore

Small boats in the upper Gulf of Thailand are advised to remain ashore from September 23–27 because of rough seas during the five-day warning period. The TMD forecasts waves of 2–3 metres, rising above 3 metres in thunderstorms.

The TMD forecasts waves of around 2 metres in the lower Gulf and upper Andaman Sea during September 23–27, exceeding 2 metres in thunderstorm areas.

Mariners in the Gulf of Thailand and Andaman Sea should navigate cautiously and avoid areas experiencing thunderstorms, the TMD said.

Flood watch covers eight eastern provinces through September 27

The Office of the National Water Resources (ONWR) has issued a separate flood warning for districts in eight eastern provinces from September 22–27, 2026. The areas identified are:

• Nakhon Nayok: Pak Phli, Ban Na and Muang Nakhon Nayok districts.
• Prachin Buri: Muang Prachin Buri, Na Di, Kabin Buri and Prachantakham districts.
• Sa Kaeo: Muang Sa Kaeo and Watthana Nakhon districts.
• Chachoengsao: Sanam Chai Khet and Tha Takiap districts.
• Chonburi: Bo Thong, Si Racha, Bang Lamung, Nong Yai and Sattahip districts.
• Rayong: Muang Rayong, Khao Chamao and Ban Khai districts.
• Chanthaburi: Makham, Tha Mai, Kaeng Hang Maeo, Pong Nam Ron, Khlung and Khao Khitchakut districts.
• Trat: Muang Trat, Khao Saming, Khlong Yai and Bo Rai districts.

The ONWR also warned of sudden rises in water levels, overflowing waterways and inundation in low-lying areas along the Nakhon Nayok River in Nakhon Nayok, Prachin Buri River in Prachin Buri, Phra Sathueng and Phra Prong canals in Sa Kaeo, and Chanthaburi River in Chanthaburi.

The TMD urged the public to plan daily activities and travel carefully during the warning period and follow official updates. Weather information is available through the department’s website and its 24-hour telephone services on 0-2399-4012-13 and 1182.

The next TMD warning is scheduled for 5am on September 23, 2026.