Thailand is facing widespread heavy rainfall and flash flood threats as a strong monsoon trough and moderate southwest monsoon sweep across the country, according to the Thai Meteorological Department.
The agency also warned of high waves in both the Andaman Sea and the Gulf of Thailand, urging caution for all marine vessels.
A moderate monsoon trough currently stretches across upper Myanmar and northern Thailand, linking to a low-pressure system over upper Laos.
At the same time, the southwest monsoon continues to prevail over the Andaman Sea, Thailand, and the Gulf, contributing to unstable weather conditions.
These systems are expected to bring widespread thundershowers and isolated heavy to very heavy rain, particularly in the North and upper Northeast.
Authorities are advising residents in these areas to stay alert for flash floods and run-off, especially near mountainous regions, rivers, and low-lying areas.
Sea conditions are expected to worsen, with waves in the upper Andaman Sea reaching up to 2 metres, and exceeding 2 metres during thunderstorms.
The lower Andaman Sea and the Gulf will see waves of 1–2 metres, with larger waves likely during stormy weather. Mariners are advised to navigate with caution and avoid storm-affected zones.
Regional Weather Forecasts (Next 24 Hours):
North:
Fairly widespread thundershowers with isolated heavy to very heavy rainfall in Mae Hong Son, Chiang Mai, Chiang Rai, Phayao, Nan, Uttaradit, Phitsanulok, Phetchabun, and Tak. Temperatures will range from 22–25°C to highs of 29–33°C.
Northeast:
Thundershowers are forecast across the region, with heavy to very heavy rain expected in Loei, Nong Khai, Bueng Kan, Nong Bua Lamphu, Udon Thani, Sakon Nakhon, Nakhon Phanom, Kalasin, Mukdahan, Yasothon, Amnat Charoen, Sisaket, and Ubon Ratchathani. Minimum temperatures will range from 22–26°C, with highs of 28–31°C.
Central:
Widespread thundershowers and isolated heavy rain are expected in Nakhon Sawan, Chai Nat, Sing Buri, Lop Buri, Saraburi, Kanchanaburi, Nakhon Pathom, and Samut Sakhon. Temperatures will range from 23–26°C to 32–34°C.
East:
Heavy rain is forecast in several provinces including Nakhon Nayok, Prachin Buri, Chachoengsao, Chonburi, Rayong, Chanthaburi, and Trat. Temperatures will range from 23–26°C to highs of 29–32°C. Sea waves are expected to reach 1–2 metres, rising higher during storms.
South (East Coast):
Scattered thundershowers are likely in Chumphon, Surat Thani, Nakhon Si Thammarat, Songkhla, Yala, and Narathiwat. Temperatures will range from 23–26°C to 30–34°C. Waves could reach 1 metre, increasing to over 2 metres during thunderstorms.
South (West Coast):
Ranong, Phang Nga, and Phuket will see scattered thundershowers and isolated heavy rainfall. Temperatures are expected to range from 23–26°C to 27–33°C. Sea conditions will see waves of 1–2 metres, with higher surges in stormy areas.
Bangkok and Surrounding Areas:
Thundershowers are expected across the capital and nearby provinces, with isolated heavy rain. Temperatures will range from 25–27°C in the morning to highs of 31–34°C.
