This data publication contains soil temperature measured at eight depths weekly (1989 - ongoing) at the Marcell Experimental Forest (MEF) in Balsam Township, Itasca County, Minnesota. The data came from five peatland / upland forest watersheds instrumented for long-term hydrological and biogeochemical research. The Marcell Experimental Forest in Itasca County, Minnesota is operated and maintained by the USDA Forest Service, Northern Research Station, and was formally established in 1962 to study the ecology and hydrology of peatlands.