Nakhon Ratchasima disaster response chief Piyachat Insawang said the drought has spread into wider areas in the province.
Four districts were earlier declared disaster areas, including Bua Yai, Prathai, Ban Lueam and Lam Thamenchai.
On Thursday, Governor Winai Buapradit announced four more districts as disaster zones including Non Daeng, Non Sung, Bua Lai and Sida.
The drought has affected 52 sub-districts in eight districts with nearly 35,000 households. Almost 450,000 rai (some 180,000 acres or 72,000 hectares) of agricultural land is hard hit.
The provincial authorities are providing assistance to residents as the governor has approved a Bt50 million fund to help the affected people.
In Nakhon Phanom, as the drought worsened in many areas, local authorities have drilled more water wells to provide ground water to ease the problem.
The provincial Royal Irrigation Department office urged farmers to refrain from growing off-season rice as the water level in the reservoir was only half of its capacity.
It was expected that the drought would continue for months as there has been no rain for four months.
Nakhon Phanom disaster services director Jureerat Thep-ard said the province has declared six of its 12 districts as disaster areas.