Heavy rains and strong waves forecast as monsoon trough persists over Thailand

TUESDAY, AUGUST 12, 2025

TMD warns of heavy rain, flash floods, and 2-metre waves as monsoon trough spans upper Thailand; Typhoon Podul heads towards Taiwan and eastern China.

The Thai Meteorological Department (TMD) on Tuesday warned of continued unsettled weather as the monsoon trough lies across upper northern Thailand and upper Laos into a low-pressure system over upper Vietnam. Meanwhile, a moderate southwest monsoon prevails over the Andaman Sea, Thailand, and the Gulf of Thailand.

Heavy to very heavy rain is expected in parts of the country, with isolated heavy rainfall in the East. Residents in these areas are advised to be alert for flash floods and overflows, especially along waterways near foothills and in low-lying areas.

Moderate winds are forecast to generate waves up to 2 metres high in the upper Andaman Sea and upper Gulf, rising above 2 metres in areas experiencing thundershowers. In the lower Andaman Sea, waves are expected to reach 1–2 metres, also exceeding 2 metres in stormy conditions. Mariners in both the Andaman Sea and the Gulf should proceed with caution and avoid thundershowers.

In addition, Typhoon Podul, currently over the Pacific Ocean, is moving towards Taiwan and is expected to make landfall in eastern China between 13 and 14 August. The storm is not forecast to enter Thailand.

The weather forecast for the next 24 hours is as follows:

North: Scattered thundershowers and isolated heavy rains in Chiang Rai, Phayao, Nan, Uttaradit, Tak, Phitsanulok and Phetchabun; minimum temperature 23-26 degrees Celsius, maximum 32-36°C. 

Northeast: Fairly widespread thundershowers and isolated heavy rains in Loei, Nong Khai, Bueng Kan, Nong Bua Lam Phu, Udon Thani, Sakon Nakhon, Nakhon Phanom, Nakhon Ratchasima and Buri Ram; minimum 23-25°C, maximum 31-34°C.

Central: Scattered thundershowers mostly in Nakhon Sawan, Uthai Thani, Lop Buri, Saraburi, Suphan Buri, Kanchanaburi and Ratchaburi; minimum 24-26°C, maximum 34-36°C. 

East: Fairly widespread thundershowers and isolated heavy to very heavy rains in Nakhon Nayok, Prachinburi, Chachoengsao, Chonburi, Rayong, Chanthaburi and Trat; minimum 23-27°C, maximum 30-35°C; waves about 2 metres high and above 2 metres high in thundershowers.

South (east coast): Scattered thundershowers and isolated heavy rains in Chumphon, Surat Thani, Nakhon Si Thammarat, Phatthalung and Songkhla; minimum 23-25°C, maximum 30-35°C; waves about a metre high and above 2 metres high in thundershowers.

South (west coast): Fairly widespread thundershowers and isolated heavy rains in Ranong, Phangnga, Phuket, Krabi, Trang and Satun; minimum 23-26°C, maximum 29-32°C; waves 1-2 metres high and above 2 metres high in thundershowers.

Bangkok metropolitan area: Scattered thundershowers and isolated heavy rains; minimum 25-27°C, maximum 32-35°C.