Flood risk remains across Thailand as monsoon begins to weaken
Very heavy rain is forecast in parts of the North, East and western South, with flash floods possible and waves exceeding 2 metres in thunderstorms.
- Despite a weakening southwesterly monsoon, heavy to very heavy rain is forecast across Thailand for the next 24 hours, maintaining a risk of flash floods and forest run-off.
- The continued rainfall is attributed to a monsoon trough situated over the North and Northeast regions of the country.
- The North, East, and the South's west coast are expected to receive isolated very heavy rain, while areas including Bangkok are forecast to experience heavy rain.
- Mariners are warned of hazardous sea conditions, with waves in the Andaman Sea and Gulf of Thailand reaching up to 2 meters or higher, especially during thunderstorms.
The Thai Meteorological Department (TMD) forecast on Friday (July 31, 2026) that heavy to very heavy rain could continue across Thailand over the next 24 hours.
Isolated very heavy rain is expected in the North, East and the South’s west coast, with isolated heavy rain in the Northeast, Central region, Bangkok and its vicinity, and the South’s east coast.
The conditions are caused by a monsoon trough across the North and Northeast. In contrast, the relatively strong southwesterly monsoon covering the Andaman Sea, Thailand and the Gulf of Thailand is expected to begin weakening.
People were advised to beware of heavy to very heavy rain and accumulated rainfall, which could cause flash floods and forest run-off, particularly on foothills near waterways and in low-lying areas.
Relatively strong wind and wave conditions in the upper Andaman Sea are also expected to ease.
Waves in the Andaman Sea and upper Gulf of Thailand will be about 2 metres high and exceed 2 metres in thunderstorms.
Waves in the lower Gulf of Thailand will be about 1 metre high, rising to 1–2 metres offshore and above 2 metres in thunderstorms.
Mariners were advised to proceed with caution and avoid sailing in areas with thunderstorms.
Forecast for Thailand from 6am on Friday (July 31, 2026) to 6am on Saturday (August 1, 2026)
North
- Thundershowers are forecast across 70% of the region, with heavy rain in Mae Hong Son, Chiang Mai, Nan, Uttaradit, Tak, Kamphaeng Phet, Sukhothai, Phitsanulok and Phichit, and isolated very heavy rain in Chiang Rai and Phetchabun.
- Minimum temperatures will range from 22–26°C and maximums from 31–35°C.
- Southwesterly winds will reach 10–20 km/h.
Northeast
- Thundershowers are forecast across 70% of the region, with isolated heavy rain in Loei, Nong Khai, Bueng Kan, Nong Bua Lamphu, Udon Thani, Sakon Nakhon, Nakhon Phanom, Chaiyaphum, Khon Kaen, Nakhon Ratchasima, Buri Ram and Surin.
- Minimum temperatures will range from 23–25°C and maximums from 29–34°C.
- Southwesterly winds will reach 10–20 km/h.
Central
- Thundershowers are forecast across 70% of the region, with isolated heavy rain in Nakhon Sawan, Uthai Thani, Lop Buri, Saraburi, Phra Nakhon Si Ayutthaya, Kanchanaburi, Ratchaburi, Nakhon Pathom and Samut Sakhon.
- Minimum temperatures will range from 24–26°C and maximums from 33–35°C.
- Southwesterly winds will reach 10–20 km/h.
East
- Thundershowers are forecast across 70% of the region, with heavy rain in Sa Kaeo, Chachoengsao and Chon Buri, and isolated very heavy rain in Nakhon Nayok, Prachin Buri, Rayong, Chanthaburi and Trat.
- Minimum temperatures will range from 23–25°C and maximums from 29–34°C.
- Southwesterly winds will reach 20–35 km/h.
- Waves will be about 2 metres high and exceed 2 metres in thunderstorms.
South (east coast)
- Thundershowers are forecast across 60% of the region, with isolated heavy rain in Phetchaburi, Prachuap Khiri Khan, Chumphon and Surat Thani.
- Minimum temperatures will range from 22–26°C and maximums from 31–34°C.
- Southwesterly winds will reach 15–35 km/h.
- Waves will be about 1 metre high, rising to 1–2 metres offshore and above 2 metres in thunderstorms.
South (west coast)
- Thundershowers are forecast across 70% of the region, with heavy rain in Phang Nga, Phuket and Krabi, and isolated very heavy rain in Ranong.
- Minimum temperatures will range from 22–24°C and maximums from 28–34°C.
- Southwesterly winds will reach 20–35 km/h.
- Waves will be about 2 metres high and exceed 2 metres in thunderstorms.
Bangkok and vicinity
- Thundershowers are forecast across 70% of the area, with isolated heavy rain.
- Minimum temperatures will range from 24–26°C and maximums from 32–34°C.
- Southwesterly winds will reach 10–25 km/h.
