Heavy rain forecast across Thailand as flood warnings widen
The Thai Meteorological Department warns of possible flash flooding from prolonged downpours, while small boats in the upper Gulf and upper Andaman Sea should stay ashore.
- Thailand's Meteorological Department has forecast heavy to very heavy rain across many regions, including the North, Northeast, Central, East, and South, from September 23 to 27.
- The severe weather is caused by an intense low-pressure area and a strengthening southwest monsoon, leading to widespread flood warnings.
- Authorities warn of potential flash floods and water torrents, particularly on foothill slopes and in low-lying areas, and advise caution during travel.
- The weather system will also strengthen winds and waves in the Andaman Sea and the Gulf of Thailand, with waves reaching over 3 meters and a warning for small boats to stay ashore.
The Thai Meteorological Department (TMD) issued a warning on Wednesday (September 23, 2026) for heavy to very heavy rain in parts of Thailand through September 27.
Heavy rain is forecast in many areas of the North, the lower Northeast, the Central region including Bangkok and its vicinity, the East and the South, with very heavy rain in some places.
The lower Northeast and the East are expected to be affected first, followed by the other regions.
An intense low-pressure area over the coast of central Vietnam is expected to move over the lower Northeast, the East and the Central region, including Bangkok and its vicinity, along a monsoon trough across upper Thailand.
Meanwhile, the south-west monsoon over the Andaman Sea, Thailand and the Gulf of Thailand will strengthen.
The department warned that heavy to very heavy rain and continued rainfall could cause flash floods and torrents of water from the hills, particularly on foothill slopes near waterways and in low-lying areas.
It advised people to avoid routes prone to repeated flooding, especially through low-lying areas where water may pool temporarily.
Winds and waves in the Andaman Sea and the Gulf of Thailand are also expected to strengthen.
Waves in the upper Gulf and upper Andaman Sea are forecast at 2–3 metres, rising above 3 metres in thunderstorms.
In the lower Gulf and lower Andaman Sea, waves are forecast at about 2 metres, exceeding 2 metres in thunderstorms.
Mariners should proceed with caution and avoid sailing in areas with thunderstorms.
Small boats in the upper Gulf and upper Andaman Sea should remain ashore until Sunday.
The department urged people to plan their daily activities and travel carefully during the period to stay safe and reduce potential impacts, and to follow its announcements.
Information is available at www.tmd.go.th or by calling 0-2399-4012-13 or 1182, 24 hours a day.
Areas forecast to receive very heavy or heavy rain on September 23
Very heavy rain
- Eastern region: Sa Kaeo, Chon Buri, Rayong, Chanthaburi and Trat.
- Central region: Bangkok and its vicinity.
Heavy rain
- Northeastern region: Chaiyaphum, Nakhon Ratchasima, Buriram, Surin, Si Sa Ket and Ubon Ratchathani.
- Central region: Uthai Thani, Chai Nat, Saraburi, Phra Nakhon Si Ayutthaya, Suphan Buri, Kanchanaburi, Ratchaburi, Nakhon Pathom, Samut Songkhram and Samut Sakhon.
- Eastern region: Nakhon Nayok, Prachin Buri and Chachoengsao.
- Southern region: Phetchaburi, Prachuap Khiri Khan, Chumphon, Surat Thani, Nakhon Si Thammarat, Songkhla, Pattani, Narathiwat, Ranong and Phang Nga.
