Fostoria is an unincorporated community in Pottawatomie County, Kansas, United States.
Fostoria is 6 miles (9.7 km) east of Olsburg. Fostoria has a post office with ZIP code 66426.
The first post office in Fostoria was established in 1884.
The climate in this area is characterized by hot, humid summers and generally mild to cool winters. According to the Köppen Climate Classification system, Fostoria has a humid subtropical climate, abbreviated "Cfa" on climate maps.