The South could experience torrential rains, the department warned.
The heavy rainfall is the result of a monsoon trough lying across the lower Central, the East and the upper South, and the intensifying southwest monsoon across the Andaman Sea and the Gulf.
Flash floods are possible in hilly areas and waterways may overflow in low-lying areas, the department warned. Motorists have been advised to drive cautiously during thunder showers.
Waves in the Andaman Sea and the Gulf of Thailand are forecast to range from one to two metres in height and exceed two metres during thunder showers. All ships should proceed with caution and avoid thundershowers, the department advised.
Thundershowers are expected in the following provinces:
North: Mae Hong Son, Chiang Mai, Tak, Phrae, Sukhothai, Uttaradit, Phitsanulok, Kamphaeng Phet and Phetchabun.
Northeast: Loei, Roi Et, Yasothon, Amnat Charoen, Chaiyaphum, Nakhon Ratchasima, Buriram, Surin, Sisaket and Ubon Ratchathani.
Central: Saraburi, Phra Nakhon Si Ayutthaya, Suphanburi, Kanchanaburi, Ratchaburi, Nakhon Pathom, Samut Sakhon, Samut Songkhram and Bangkok metropolitan area.
East: Nakhon Nayok, Prachinburi, Sa Kaeo, Chachoengsao, Chonburi, Rayong, Chanthaburi and Trat.
South: Phetchaburi, Surat Thani, Nakhon Si Thammarat, Phatthalung, Songkhla, Pattani, Yala, Narathiwat, Ranong, Phang Nga, Phuket, Krabi, Trang and Satun.