The problem of analyzing anthropogenic carbon dioxide impact on the environment necessitates research on the dynamics of soil carbon. Thermal parameters (heat capacity, thermal conductivity and thermal diffusivity) have a significant effect on soil formation and are essential in estimating CO2 transfer and production. While these processes depend on soil texture and a number of other factors, a relevant task is to mathematically describe the thermal regime of soils in a specific area. In this paper, we propose a model of daily temperature wave fluctuation for the forest sandy soils of Eastern Fennoscandia, assuming the medium is heterogeneous. It is tested by comparing real temperature measurements with the simulation results produced by the model proposed here and the Chudnovsky – Nerpin model.