Many parts of Chiang Mai were flooded on Sunday after the Ping River overflowed due to continuous, heavy rain brought by tropical storm Mulan.
The storm also hit several provinces in the Northeast and East of the country.
Meanwhile, the Disaster Prevention and Mitigation Department warned the residents of Chiang Rai, Nan, Ang Thong and Ayutthaya to beware of flash floods on Sunday.
Residents have also been advised to follow weather updates, take care while driving and beware of poisonous creatures and short circuits.
The department also said that 26 provinces face flooding due to runoffs. They are:
Northeast: Loei, Nong Khai and Nakhon Phanom
Central: Samut Sakhon, Samut Songkhram, Samut Prakan, Chachoengsao, Chonburi, Rayong, Chanthaburi, Trat, Phetchaburi, Prachuap Khiri Khan and Bangkok
South: Chumphon, Surat Thani, Nakhon Si Thammarat, Songkhla, Pattani, Narathiwat, Ranong, Phang Nga, Phuket, Krabi, Trang and Satun.