Photo: Dibakar Roy / Pexels
Thailand's Meteorological Department (TMD) has issued a warning for 26 and 27 September 2026, forecasting heavy to very heavy rain across the country. Bangkok had prolonged rain on 25 September and most of the city flooded. On the 26 September list, 47 provinces in the North, Northeast, Central, East and upper South face possible flash floods and overflows. An active low-pressure cell over the lower Central region is behind it, and the southwest monsoon is strengthening at the same time.
What is causing the rain
An active low-pressure cell is sitting over the lower Central region, Bangkok and nearby provinces. It is expected to move toward the Central region along the monsoon trough over upper Thailand. Meanwhile, the southwest monsoon over the Andaman Sea, the South and the Gulf of Thailand is getting stronger.
Bangkok flooding
Rain in Bangkok was prolonged on 25 September, and most of the city flooded. Bang Kapi was hit especially hard: Khlong Saen Saep overflowed and left roads impassable. Morning rain also slowed traffic on major routes.
What the TMD advises
- Beware of heavy to very heavy rain and accumulated rainfall.
- Flash floods, overflows and landslides are possible, especially along waterways near foothills and in lowlands.
- Avoid routes that flood repeatedly.
- Low-lying areas may see short-term waterlogging.
Regional forecast
| Region | Rain | Temperatures | Wind and waves |
|---|---|---|---|
| Bangkok and vicinity | Widespread thundershowers, scattered heavy to very heavy | Low 22-24°C, high 26-29°C | Variable, 10-25 km/h |
| Central (14 provinces) | Fairly widespread thundershowers, scattered heavy to very heavy | Low 22-24°C, high 28-32°C | Variable, 10-25 km/h |
| East (8 provinces) | Fairly widespread thundershowers, scattered heavy, very heavy in isolated spots | 22-29°C | Variable, 20-40 km/h. Waves 2-3 m, over 3 m in thundershowers |
| North | Scattered thundershowers, isolated heavy. Very heavy possible in parts of Tak and Phetchabun | Low 22-26°C, high 31-35°C | Easterly, 10-20 km/h |
| Northeast | Fairly widespread thundershowers, isolated heavy. Very heavy possible in parts of Nakhon Ratchasima | 22-33°C | Northeasterly, 10-25 km/h |
| South east coast | Fairly widespread thundershowers, isolated heavy in Chumphon and Surat Thani. Very heavy possible in parts of Phetchaburi and Prachuap Khiri Khan | Low 21-25°C, high 27-35°C | See below |
| South west coast | Scattered thundershowers, isolated heavy in Ranong and Phang Nga | 23-36°C | See below |
Provinces named in each region
- Central: Nakhon Sawan, Uthai Thani, Chai Nat, Sing Buri, Ang Thong, Lop Buri, Saraburi, Suphan Buri, Ayutthaya, Kanchanaburi, Nakhon Pathom, Ratchaburi, Samut Sakhon and Samut Songkhram.
- East: Nakhon Nayok, Prachin Buri, Sa Kaeo, Chachoengsao, Chon Buri, Rayong, Chanthaburi and Trat.
- North: Mae Hong Son, Chiang Mai, Lamphun, Lampang, Uttaradit, Sukhothai, Kamphaeng Phet, Phichit and Phitsanulok, plus Tak and Phetchabun.
- Northeast: Loei, Nong Bua Lam Phu, Khon Kaen, Chaiyaphum, Buri Ram, Surin and Si Sa Ket, plus Nakhon Ratchasima.
Winds and waves on the coasts
South east coast
- From Surat Thani northward: northwesterly winds of 20-35 km/h, with waves about 2 m.
- From Nakhon Si Thammarat southward: westerly winds of 15-35 km/h, with waves of 1-2 m.
- In both areas, waves may exceed 3 m in thundershowers.
South west coast
- From Phang Nga northward: westerly winds of 20-35 km/h, with waves about 2 m.
- From Phuket southward: southwesterly winds. The source text ends here, so the speed and wave details for this stretch are not available.
Related reports
- The TMD earlier flagged a nationwide flash-flood risk for 23 to 27 September.
- Pattaya had overnight flooding earlier this week, and a foreign man was reported missing.
Information sourced from The Thaiger.