Blanchester, Ohio is located in the southwestern part of the state and has a humid continental climate characterized by warm summers and cold winters. The area is drained by the East Fork Little Miami River and its tributaries, which provide opportunities for fishing, boating, and other water-based activities. The hydrology constituents in the area include nitrate, which can come from agricultural runoff, and sediment, which can result from construction or erosion. Outdoor recreation opportunities in Blanchester include hiking and biking on the nearby Little Miami Scenic Trail, as well as camping and picnicking at the Cowan Lake State Park. The park also offers opportunities for swimming, boating, and fishing.