Heavy rain is forecast for at least 50 provinces, including Bangkok, through into Sunday, with temperatures to plunge in upper Thailand from Monday to Wednesday.
The monsoon trough will move across the lower North, the upper Central and the Northeast region before the arrival of a moderate high pressure system moving in from China that will collide with hot air over the North and the Northeast from Sept 20-22, the weather office said on Friday morning.
This will bring heavy to very heavy rain and gusty winds to many areas across the country through into Sunday. In upper Thailand temperatures are forecast to drop 3-5°C from Monday to Wednesday.
The forecast is for downpours in more than 50 provinces, including Bangkok, from Friday.
The affected areas are: 14 provinces in the North (Mae Hong Son, Chiang Mai, Lamphun, Lampang, Phrae, Phayao, Nan, Phitsanulok, Phichit, Uttaradit, Tak, Sukhothai, Kamphaeng Phet and Phetchabun); 10 in the Northeast (Chaiyaphum, Nakhon Ratchasima, Buri Ram, Surin, Si Sa Ket, Roi Et, Yasothon, Mukdahan, Amnat Charoen and Ubon Ratchathani); 14 in the Central Plains (Ratchaburi, Kanchanaburi, Samut Songkhram, Samut Sakhon, Nakhon Pathom, Suphan Buri, Uthai Thani, Chai Nat, Nakhon Sawan, Ang Thong, Sing Buri, Lop Buri, Saraburi and Ayutthaya); Bangkok and its surrounding provinces; 8 in the East (Nakhon Nayok, Prachin Buri, Sa Kaeo, Chachoengsao, Chon Buri,Rayong, Chanthaburi and Trat), and 4 in the South (Phetchaburi, Prachuap Khiri Khan, Chumphon and Ranong)
On Saturday and Sunday, heavy rain and gusty winds are expected to affected 11 provinces in the North (Chiang Mai, Chiang Rai, Lamphun, Lampang, Phayao, Phrae, Nan, Nan, Phitsanulok, Phichit, Uttaradit and Phetchabun), 3 in the Northeast (Surin, Si Sa Ket and Ubon Ratchathani), 11 in the Central Plains (Ratchaburi, Kanchanaburi, Samut Songkhram, Samut Sakhon, Nakhon Pathom, Suphan Buri, Chai Nat, Ang Thong, Sing Buri and Ayutthaya), Bangkok and surrounding areas, 8 provinces in the East (Nakhon Nayok, Prachin Buri, Sa Kaeo, Chachoengsao, Chon Buri, Rayong, Chanthaburi and Trat) and 2 in the South (Phetchaburi and Prachuap Khiri Khan).
The department advised people to closely follow weather reports and warnings.
Heavy rain triggers forest-run that flows into buildings and students' living quarters at a school in Sai Yok district, Kanchanaburi late Thursday night. No injuries were reported. (Photo by Piyarat Chongcharoen)