This dataset contains frost depth data collected every two weeks in two peatlands instrumented for hydrologic monitoring at the Marcell Experimental Forest (MEF) from 1985–ongoing, only from February until the end of frost during Spring. The variables measured are depth to frost layer, frost thickness, and frost occurrence as percent of area. The three measurements provide information on the depth, duration, and extent of a frost layer. 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.