Heavy rain and strong waves expected in parts of Thailand due to southwest monsoon

Heavy rain forecast for northern, northeastern, eastern, and southern Thailand. High waves expected in the Andaman Sea and Gulf. Mariners advised caution.

Thailand is expected to experience isolated heavy to very heavy rain as the moderate southwest monsoon continues to prevail over the Andaman Sea, Thailand, and the Gulf of Thailand, while a low-pressure cell covers upper Laos and upper Vietnam, the Thai Meteorological Department said on Wednesday.

Heavy rain is likely in the North, upper Northeast, East, and South, particularly along foothills, low-lying areas, and waterways, where flash floods, runoff, and landslides may occur. Residents in these areas are urged to remain vigilant, the department said.



Maritime conditions remain rough, with waves in the upper Andaman Sea reaching 2 metres, and exceeding that in areas experiencing thundershowers. In the lower Andaman Sea and the upper Gulf, waves are expected to range from 1 to 2 metres, rising above 2 metres during storms.

All vessels in the Andaman Sea and the Gulf should proceed with caution and avoid navigating through storm-affected areas, the department warned.

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

North: Scattered thundershowers and isolated heavy rains in Mae Hong Son, Chiang Mai, Chiang Rai, Phayao, Nan, Lamphun, Lampang and Tak; minimum temperature 24-26 degrees Celsius, maximum 31-35°C.

Northeast: Scattered thundershowers and isolated heavy rains in Nong Khai, Bueng Kan, Udon Thani, Sakon Nakhon and Nakhon Phanom; minimum 23-25°C, maximum 32-35°C.

Central: Scattered thundershowers mostly in Uthai Thani, Suphan Buri, Saraburi, Kanchanaburi and Ratchaburi; minimum 25-27°C, maximum 33-35°C.

East: Scattered thundershowers and isolated heavy rains in Nakhon Nayok, Prachin Buri, Chanthaburi and Trat; minimum 24-28°C, maximum 30-34°C; waves 1-2 metres high and above 2 metres high in thundershowers.

South (east coast): Scattered thundershowers and isolated heavy rains in Chumphon, Surat Thani and Nakhon Si Thammarat; minimum 23-26°C, maximum 32-34°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, Phang Nga and Phuket; minimum 21-24°C, maximum 29-33°C; waves 1-2 metres high and above 2 metres high in thundershowers.

Bangkok metropolitan area: Scattered thundershowers; minimum 26-27°C, maximum 32-35°C.

(2025/06/25-00:00)