Climate and its variability have a significant influence on the thermal regime of Permafrost soils. Therefore, it is important to understand the small scale processes and dynamics of heat transport in frozen ground. By means of measurement data from a study site at Samoylov Island in the Lena River Delta in Northern Siberia climate as well as the thermal and hydrological state of the soil is analyzed for a time series of two years from 2003-2005. The study site is characterized as a wet polygonal tundra, showing distinctive permafrost structures that influence the measurement results. Furthermore, a temperature projection model is applied to the data set, fitting the simulated soil temperature values to the measurements. As the model is based on the transfer function method using the equation of pure conductive heat flow, the main estimation parameter characterizes the effective thermal diffusivity of the soil. For winter periods deviations between model and measurement do not exceed ±0.3 ◦C and the thermal diffusivity is in the expected order of magnitude. In addition, these deviations are interpreted qualitatively with regard to non-conductive processes and the heterogeneity of the soil, giving essential information about the complexity of the thermal soil system.