Nyamira County is located in the former Nyanza Province. It covers an area 899.3 sq km with temperatures range of 10.1 °C to 28.7 °C, and rainfall of between 600mm and 2,300mm per annum. The county has 4 local authorities (Nyamira County Council, Town Councils of Nyamira, Nyansiongo and Keroka) Nyamira Town is the administrative capital.
Agriculture is the main economic countributor to the county. Main cash crops are tea and pyrethrum. Others include sugarcane, bananas maize, dairy and livestock products.
The county experiences experience relatively good weather patterns with rainfall occurring regularly throughout the year. However opportunities exist for development of large-scale irrigation schemes.