Residents in affected areas are advised to remain cautious of severe weather and take care of their health due to changing weather conditions, the department said.
Meanwhile, the westerly and southwesterly winds prevail over the Andaman Sea, the South and the Gulf of Thailand, bringing isolated heavy rains to the South.
People in the South should beware of heavy rains that may cause flash flood and overflows, especially along the waterways, near foothills and lowlands, the department warned.
Waves in the Andaman Sea and the Gulf are likely about 1 metre high and above 2 metres high in thundershowers. All ships in both seas should keep off thundershowers, the department added.
The weather forecast for the next 24 hours is as follows:
North: Hot to very hot day with isolated thundershowers and gusty winds mostly in Sukhothai, Tak, Kamphaeng Phet, Phitsanulok and Phetchabun; minimum temperature 22-27 degrees Celsius, maximum 37-40°C.
Northeast: Hot day with isolated thundershowers and gusty winds mostly in Loei, Nong Khai, Bueng Kan, Sakon Nakhon, Nakhon Phanom, Chaiyaphum, Khon Kaen, Nakhon Ratchasima, and Buriram; minimum 24-27°C, maximum 36-38°C.
Central: Hot day with isolated thundershowers and gusty winds mostly in Nakhon Sawan, Uthai Thani, Chainat, Suphan Buri, Kanchanaburi, Ratchaburi, and Samut Songkhram; minimum 24-28°C, maximum 37-39°C.
East: Hot day with isolated thundershowers mostly in Chachoengsao, Chonburi, Rayong, Chanthaburi and Trat; minimum 24-28°C, maximum 33-37°C; waves about a metre 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 34-36°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, Phuket, Krabi and Trang; minimum 23-25°C, maximum 30-33°C; waves about a metre high and above 2 metres high in thundershowers.
Bangkok metropolitan area: Hot day with isolated thundershowers; minimum 26-28°C, maximum 35-38°C.