Monsoon conditions heighten flash flood risk across eastern Thailand
Thailand's weather agency forecasts heavy rain in parts of the country and very heavy falls in the East, warning of flash floods and waves above three metres in the upper Andaman Sea.
- The Thai Meteorological Department has forecast heavy to very heavy rain across Thailand, with the East being particularly affected, due to a monsoon trough and a strong southwest monsoon.
- These weather conditions have increased the danger of flash floods and forest run-off, especially on foothill slopes, near waterways, and in low-lying areas.
- The forecast specifically highlights a risk of very heavy rain in the eastern provinces of Chanthaburi and Trat.
- Residents in affected areas have been urged to remain alert to the dangers posed by heavy and accumulated rainfall.
The Thai Meteorological Department (TMD) forecast at 5pm on Friday (August 14, 2026) that Thailand would continue to experience heavy rain in some areas over the next 24 hours, with very heavy rain in the East.
The conditions were caused by a monsoon trough extending across Myanmar and the upper North into a low-pressure area over upper Vietnam, together with a rather strong southwest monsoon prevailing over the Andaman Sea, Thailand and the Gulf of Thailand.
People in the affected areas were urged to remain alert to the dangers posed by heavy rain and accumulated rainfall, which could cause flash floods and forest run-off, particularly on foothill slopes near waterways and in low-lying areas.
Water could also overflow riverbanks in the Northeast.
Conditions in the upper Andaman Sea were expected to be rather rough, with waves 2–3 metres high and exceeding 3 metres during thunderstorms.
Mariners were advised to exercise caution and avoid sailing in areas of thunderstorms, while small boats in the upper Andaman Sea should remain ashore.
TMD reports rain moving into three provinces
The TMD reported light to moderate rain, with heavy rain in some places, over Bangkok’s Prawet, Lat Krabang, Khlong Sam Wa and Nong Chok districts, as well as Samut Prakan, Pathum Thani, Nakhon Nayok, Chachoengsao and Prachin Buri.
The rain was moving eastwards into Nakhon Nayok, Chachoengsao and Prachin Buri.
From 5.30pm to 6pm, the rain was expected to remain over Nakhon Nayok, Chachoengsao and Prachin Buri.
No rain cells were detected over Bangkok or the wider metropolitan area.
Forecast for Thailand from 6pm on Friday (August 14) to 6pm on Saturday (August 15)
North
- Thunderstorms are forecast across 60% of the region, with heavy rain in some parts of Mae Hong Son, Chiang Mai, Chiang Rai, Phayao, Nan and Tak.
- Minimum temperatures will be 22–28°C and maximum temperatures 32–35°C.
- Southwesterly winds will blow at 10–20 km/h.
Northeast
- Thunderstorms are forecast across 60% of the region, with heavy rain in some parts of Udon Thani, Nong Khai, Bueng Kan, Sakon Nakhon, Nakhon Phanom, Mukdahan, Amnat Charoen and Ubon Ratchathani.
- Minimum temperatures will be 24–26°C and maximum temperatures 33–35°C.
- Southwesterly winds will blow at 10–20 km/h.
Central
- Thunderstorms are forecast across 40% of the region, with heavy rain in some parts of Saraburi and Kanchanaburi.
- Minimum temperatures will be 25–26°C and maximum temperatures 34–36°C.
- Southwesterly winds will blow at 10–25 km/h.
Bangkok and vicinity
- Thunderstorms are forecast across 60% of the area, with heavy rain in some places.
- Minimum temperatures will be 26–27°C and maximum temperatures 32–34°C.
- Southwesterly winds will blow at 10–25 km/h.
East
- Thunderstorms are forecast across 60% of the region, with heavy rain in some parts of Nakhon Nayok and Prachin Buri and very heavy rain in some parts of Chanthaburi and Trat. Minimum temperatures will be 24–28°C and maximum temperatures 31–34°C.
- Southwesterly winds will blow at 20–35 km/h.
- Waves will be about 2 metres high and exceed 2 metres during thunderstorms.
South (east coast)
- Thunderstorms are forecast across 40% of the region, mainly in Chumphon, Surat Thani, Nakhon Si Thammarat, Songkhla, Yala and Narathiwat.
- Minimum temperatures will be 23–26°C and maximum temperatures 31–35°C. Southwesterly winds will blow at 20–35 km/h.
- Waves will be 1–2 metres high, about 2 metres offshore and above 2 metres during thunderstorms.
South (west coast)
- Thunderstorms are forecast across 60% of the region, with heavy rain in some parts of Trang and Satun.
- Minimum temperatures will be 23–27°C and maximum temperatures 32–35°C.
- From Phang Nga northwards, southwesterly winds will blow at 20–40 km/h. Waves will be 2–3 metres high and exceed 3 metres during thunderstorms.
- From Phuket southwards, southwesterly winds will blow at 15–35 km/h. Waves will be 1–2 metres high and exceed 2 metres during thunderstorms.
