TMD warns of very heavy rain in East, waves above 3 metres

The Thai Meteorological Department (TMD) has warned of continued isolated heavy rain across Thailand on Friday (August 14, 2026), with very heavy downpours forecast in parts of the East and waves exceeding 3 metres in thundershowers in the upper Andaman Sea.

The conditions are being driven by a monsoon trough stretching across Myanmar, upper Laos and upper Vietnam, together with a rather strong southwest monsoon covering the Andaman Sea, Thailand and the Gulf of Thailand.

The TMD warned that heavy and accumulated rainfall could cause flash floods and forest run-off, particularly on foothill slopes near waterways and in low-lying areas. Rivers could also overflow their banks in the Northeast.

Forecast from 7am Friday to 7am Saturday

North

• Thundershowers are forecast across 60% of the region, with isolated heavy rain in Mae Hong Son, Nan and Tak.
• Temperatures will range from lows of 22–28°C to highs of 32–35°C.
• Southwesterly winds will reach 10–20 km/h.

Northeast

• Thundershowers are forecast across 60% of the region, with isolated heavy rain in Udon Thani, Nong Khai, Bueng Kan, Sakon Nakhon, Nakhon Phanom and Mukdahan.
• Temperatures will range from lows of 24–26°C to highs of 32–35°C.
• Southwesterly winds will reach 10–20 km/h.

Central region

• Thundershowers are forecast across 40% of the region, with isolated heavy rain in Saraburi and Kanchanaburi.
• Temperatures will range from lows of 24–27°C to highs of 34–36°C.
• Southwesterly winds will reach 10–25 km/h.

East

• Thundershowers are forecast across 60% of the region.
• Isolated heavy rain is expected in Nakhon Nayok and Prachin Buri, with very heavy rain in Chanthaburi and Trat.
• Temperatures will range from lows of 24–28°C to highs of 30–34°C.
• Southwesterly winds will reach 20–35 km/h.
• Waves will be about 2 metres high and may exceed 2 metres in thundershowers.

South, east coast

• Thundershowers are forecast across 40% of the region, mainly in Chumphon, Surat Thani and Nakhon Si Thammarat.
• Temperatures will range from lows of 23–26°C to highs of 31–36°C.
• Southwesterly winds will reach 20–35 km/h.
• Waves will be 1–2 metres high, about 2 metres offshore and above 2 metres in thundershowers.

South, west coast

• Thundershowers are forecast across 60% of the region, with isolated heavy rain in Ranong and Phang Nga.
• Temperatures will range from lows of 23–27°C to highs of 31–36°C.
• From Phang Nga northwards, southwesterly winds will reach 20–40 km/h, with waves of 2–3 metres and above 3 metres in thundershowers.
• From Phuket southwards, southwesterly winds will reach 15–35 km/h, with waves of 1–2 metres and above 2 metres in thundershowers.

Bangkok and vicinity

• Thundershowers are forecast across 60% of the area, with isolated heavy rain.
• Temperatures will range from lows of 26–27°C to highs of 32–34°C.
• Southwesterly winds will reach 10–25 km/h.