Many insects spend a portion of their life in soil, where their phenology and survival can be modeled, in part, as a function of temperature. We addressed estimating soil temperatures along vertical profiles to depths of 50 cm in a Hagerstown silt loam. Horizontal temperature homogeneity at small spatial scales was confirmed. Relationship between air and soil temperature was modeled from 25,920 field observations collected at 12 heights (-50cm to +200cm) using heat equation. Also, we compared an asymmetrical step function to the traditional sine/cosine method for interpolation of temperature over time. Daily maximum and minimum air temperatures were sufficient to accurately interpolate both a temporal and spatial temperature profile at varying depths in soil.