The close relationship between air and ground temperatures has been used to reconstruct paleoclimate conditions from ground temperatures. Unfortunately, the presence of snow decouples air and ground temperatures and obscures their relationship. The objective of this paper is to investigate the role that snowpack conditions play in affecting the relationship between air and soil temperatures. The annual thermal offset between mean annual soil and air temperatures is examined over a 12 year period (1990--2002) at Fargo, ND, using observed soil temperatures along with simulations from a physically based snowpack model. Early season snow cover does not necessarily lead to large thermal offsets. These snowpacks, while low in density, also tended to be shallow and therefore do not provide much thermal insulation. Winter snowpacks explain a greater portion of the annual thermal offset. While denser than fall snowpacks, the extra depth and longer persistence leads to superior insulation of the ground.