The objectives of the study of winter soil temperatures under a sod cover were to show the configuration of the soil isotherm patterns, in particular that of 0C, and to determine which soil thermal characteristics can be estimated by the snow cover. The temperature data were obtained at the University of Minnesota Agricultural Experiment Station plots on the St. Paul Campus with copper-constantan thermocouples during the winters of 1961-62 through 1968-69. Based upon the depth and persistence of the snow cover there were in effect 3 kinds of winters: one with deep and persistent snow cover, one with very little snow cover and all other winters. There was a close relationship between the kinds of winters and the maximum depth to which the 0C isotherm penetrated, and a fair relationship to the rate of movement of the 0C isotherm into the soil. The combination of type of winter (snow depth and duration) with cumulative heating degree days proved to be a simple and effective means of predicting the maximum freezing depth. (Author)