Increasing production of artificial snow in ski resorts is controversially discussed, but only few investigations have been carried out systematically to specify the environmental impacts. We measured snow depth and density from groomed ski pistes (runs) with compacted snow and their effects on ground temperatures and timing of snowmelt. We analyzed groomed pistes with and without artificial snow (10 each) as well as adjacent ungroomed off-piste control plots beside the piste. On pistes with natural snow, the thin and compacted snow cover led to severe and long lasting seasonal soil frost. On pistes with artificial snow, soil frost occurred less frequently because of increased insulation due to the greater snow depth. However, due to the greater snow mass, the beginning of the snow-free season was delayed by more than 2 wk. Average winter ground temperatures under a continuous snow cover were decreased by approximately 1 degrees C on both piste types compared with off-piste control plots. The results suggest that the heat balance of alpine soils is changed by both piste types, either by an extensive heat loss on pistes with natural snow or by prolonged snow cover on pistes with artificial snow.