Accurately modeling the duration and extent of soil heating from prescribed fires and wildfires is vital to predicting many second-order fire effects, including development of soil hydrophobicity and other biological, chemical, and physical effects. Advancements have been made in the process-based soil heating models that consider soil heating a function of soil characteristics, fuel consumption, and moisture content. Nevertheless, current models of soil heating during fires have not been sufficiently evaluated under a variety of actual burning, soil, or fuel conditions. We assessed Massman's 2015 soil heating model which models soil temperature, soil water potential and soil water vapor under a variety of soil, fuel, and burning conditions with existing field-collected datasets. This complex model better incorporates the physio-chemical processes that describe evaporation of soil moisture and the transport of soil water vapor and liquid water that occur during fires. Improvements to the model were made to stabilize soil moisture estimates. The new version, referred to as Massman's 2018 model, was compared to Campbell's 1995 soil heating model. We tested both soil heating models using standard statistical techniques and several existing soil heating datasets. The results indicate that the Massman's 2018 model is an improvement compared to the Campbell model, showing higher accuracy and less errors when predicting soil temperature and soil moisture for various prescribed fires and pile burns scenarios. We have incorporated Massman’s model into the First Order Fire Effects Model (FOFEM 6.6 and greater). This soil heating model has a user-friendly interface and is an improved assessment tool for fire managers.