The affected districts of the northeastern province are: Ban Khwao, Chatturat, Muang, Noen Sa-nga, and Khon Sawan.
People are advised to monitor the water level closely and move their belongings and animals to higher places, said the office.
It added that the province had ordered local administration organisations to keep water pumps, vehicles, tools and personnel for public evacuation and flood relief on standby 24 hours a day from Saturday.
Several agricultural and residential areas in Chaiyaphum have been flooded since earlier this week as a result of heavy rains, which consequently led to water runoffs from Phang Hoei and the Phu Lan Kha mountain ranges, located to the west of the province, flowing towards the Chi River to the east.
On Friday deputy provincial governor Orn-Apha Loweera and irrigation officials visited the Bueng Lahan Lake in Chatturat district to investigate the flood situation. Officials also eliminated aquatic weeds at the lake’s flowing point into the Chi River to prevent them from forming blockades downstream.
The Thai Meteorological Department forecast on Saturday that the monsoon trough covering most of upper Thailand would bring heavy rain to the upper country and very heavy rain to certain areas of the northern and northeastern regions. It advised people in these areas to be cautious of flash floods and water runoffs, especially in areas near rivers and valleys.