The tropical storm Molave has been downgraded into the Category 2 Tropical depression over Ubon Ratchathani, said the Meteorological Department.
Isolated heavy to very heavy rain with strong wind is likely in upper Thailand.
People, living in disaster-prone areas in the North, the Northeast, the East and the South are warned of heavy rain, which could trigger flash flood and forest run-off.
In Nakhon Ratchasima, the Mun River has overflowed its banks, flooding low-lying areas in Chakkarat district.
A local hospital in Khokphra sub-district has been under water, forcing medical staff to move out to a makeshift hospital unit at a community building.