Heavy rain and flash flood risk as monsoon strengthens across Thailand

More rains and isolated heavy showers are expected in the lower Central region, including Bangkok metropolitan area, the East, and the South.

The moderate monsoon trough will move south, crossing the North, Northeast, and upper Central regions into the low-pressure cell over the middle South China Sea. Meanwhile, the moderate southwest monsoon will strengthen over the Andaman Sea, lower Central, South, East, and Gulf regions of Thailand, bringing increased rainfall, the Thai Meteorological Department said on Saturday.

More rains and isolated heavy showers are expected in the lower Central region, including Bangkok metropolitan area, the East, and the South. People in these areas should be cautious of heavy to very heavy rainfall and potential water accumulation that may lead to flash floods and overflows, especially along waterways, near foothills, and in lowland areas. Farmers are advised to protect crops from potential damage, the department added.



The strengthening winds are causing waves in the Andaman Sea to rise to 2-3 metres, with waves exceeding 3 metres in areas with thunderstorms. In the Gulf, waves are expected to reach 1-2 metres, rising above 2 metres during thunderstorms.

All ships in the Andaman Sea and the Gulf of Thailand are urged to proceed with caution and avoid thunderstorms. Small boats in the Andaman Sea should remain ashore for safety, the department warned.

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

North: Scattered thundershowers mostly in Mae Hong Son, Chiang Mai, Chiang Rai, Phayao, Nan, Uttaradit, Tak and Phitsanulok; minimum temperature 23-26 degrees Celsius, maximum 33-37°C. 

Northeast: Scattered thundershowers mostly in Loei, Nong Khai, Bueng Kan, Nong Bua Lamphu, Udon Thani, Sakon Nakhon, Nakhon Phanom, Kalasin, Chaiyaphum, Khon Kaen, Nakhon Ratchasima and Buriram; minimum 24-27°C, maximum 33-36°C.

Central: Scattered thundershowers and isolated heavy rain in Kanchanaburi, Ratchaburi, Nakhon Pathom, Samut Songkhram and Samut Sakhon; minimum 24-27°C, maximum 35-37°C. 

East: Scattered thundershowers and isolated heavy rain in Nakhon Nayok, Prachin Buri, Rayong, Chanthaburi and Trat; minimum 24-28°C, maximum 32-36°C; waves about 1-2 metres high and above 2 metres high in thundershowers.

South (east coast): Scattered thundershowers mostly in Chumphon, Surat Thani, Nakhon Si Thammarat, Phatthalung, Songkhla, Yala and Narathiwat; minimum 23-26°C, maximum 32-35°C; waves about 1-2 metres high and above 2 metres high in thundershowers.

South (west coast): Fairly widespread thundershowers and isolated heavy rain in Ranong, Phang Nga, Phuket, Krabi, Trang and Satun; minimum 23-25°C, maximum 30-33°C; waves about 2-3 metres high and above 3 metres high in thundershowers.

Bangkok metropolitan area: Scattered thundershowers and isolated heavy rains; minimum 24-27°C, maximum 34-36°C.

(2025/06/07-00:00)