Clothing resistance parameter rcl and potential evapotranspiration (PET), a major component of Thornthwaite type climate classifications, are used as thermal climate indicators for characterizing the thermal climate of the Carpathian region. rcl is simulated by a model based on clothed human body energy balance considerations. rcl refers to a walking human in outdoor conditions, whose somatotype can differ. Somatotype shapes are determined by applying the Heath–Carter somatotype method. PET is estimated using only air temperature and latitude as inputs. In addition rcl is linked to PET. The annual mean of rcl is statistically interconnected with annual sum of PET, and the annual fluctuation of rcl (drcl = rclmax − rclmin) with the annual fluctuation of PET (dPET = PETmax − PETmin). The Carpathian region's thermal climate is analysed by comparing PET results with rcl model results and rcl results obtained by statistical link. We showed that rcl model results are strongly sensitive to human body somatotype variations. It is also shown that the spatial heterogeneity of thermal climates is the lowest in the lowlands and the highest in the mountains. The spatial heterogeneity of rcl and drcl values obtained by statistical link is comparable to the spatial heterogeneity of PET, but is lower than that obtained from the rcl model. Similarly to rcl model results, rcl results obtained by statistical link are also sensitive to human body somatotype variations. All these results suggest that statistical connections between rcl and PET and drcl and dPET can be used as subunits in Thornthwaite type climate classifications to obtain human thermal climate information. Lastly, areas with the largest thermal contrast are reproduced in terms of both the annual sum of PET and the rcl, which is obtained by both the model and the statistical link.