A grassy field and a bare soil there are the basic standard areas in measurements of soil temperature. The study comprised statistical and climatological analysis of long-term (1966-2006) runs of hourly, monthly and yearly differences between soil temperatures of grass-covered and bare soil in the Agri- and Hydrometeorology Wrocław-Swojec Observatory. The analyses covered thermal changes at soil depths of 1-2, 5, 10, 20, 50 and 100cm. The long-term variability of the temperature differences under analysis, as observed in the seasonal distributions, is significantly related to variation trends of the basic agrimeteorological elements – air temperature, insolation, rainfalls, and ground water levels. In this aspect, comparison was made of the variability of the differential parameters under study, i.e. soil temperatures of grassland and bares soil (Ttr-Tug), emphasizing its relations with the long-term air circulation dynamics. This permitted identification of the buffering role of the vegetation factor relative to the on-going climatic changes.