Shallow or temporary snow cover allows heat and water to move between snow and soil, making it difficult to model soil behavior due to freeze-thaw cycles and changing water flow. To address this, we developed a thermo-hydro-mechanical (THM) soil model that simulates heat transfer, water movement in freezing conditions, and small soil deformations. We tested the model using 2014–2015 field data from the Jeff Dozier Snow Study Site on Mammoth Mountain, California, where the soil is sandy and highly permeable. The model results were compared with measured ground temperature, soil moisture, and snowmelt infiltration. Our findings show that accurately modeling soil behavior in such conditions requires either detailed surface boundary data, including snowmelt, or coupling with a snow model.