In light of the importance of soil temperatures at shallow depths as the source of the deep (terrestrial) soil temperature variations, this study examined how variations of the former have been associated with the surface air temperature (SAT) variations, testing the hypothesis that the deep soil temperatures, e.g., borehole temperatures, can be used as a proxy of the SAT. Over 153 stations in the Eurasian continent were used in the study. Its major results show a dominant SAT effect on the soil temperatures across the continent and over the seasons, but also depict precipitation influences in some regions, most significantly in winter. The latter suggests that the terrestrial soil temperatures may be more accurately considered as a proxy of very low frequency varying climate conditions at the surface.