Greenville, Ohio experiences a humid continental climate, characterized by hot summers and cold winters. The town is situated on the banks of the Greenville Creek, which is a tributary of the Great Miami River. The water quality of the Greenville Creek is monitored by the Ohio Environmental Protection Agency and has been found to have elevated levels of phosphorus and sediment. Outdoor recreation opportunities in Greenville include hiking, biking, and fishing at the nearby Shawnee Prairie Preserve and Lake St. Clair Park. The Greenville City Park also offers amenities such as playgrounds, picnic areas, and a swimming pool. Additionally, the Darke County Fairgrounds hosts a variety of events throughout the year, including the annual Great Darke County Fair.