Micrometeorologists have long recognized the role of the heat-storage capacity of the soil in such problems as the occurrence of frost and dew, forecasting of maximum and minimum temperatures, partition of solar energy between the soil and atmosphere, etc. Meteorologists are becoming increasingly aware of the importance of thermal properties of the soil on larger-scale processes such as the modification of air masses, formation of tornadoes, development of weather systems, and the general circulation. The heat energy stored per unit area by the soil can be calculated if the temperature and heat capacity of the soil as functions of time and depth are known. In this investigation, the daily and annual cycles of soil temperature have been calculated from the soil temperature data collected by the Meteorology Group at the Argonne National Laboratory. Since data on soil moisture were not available, it was necessary to estimate the heat capacity of the soil from several spot measurements of the heat-capacity profiles and the rainfall record.