An approximate numerical method is presented coupling the transfer of water, heat and water vapour in a soil. The system is used to predict in time, soil temperature profiles under simulated surface fire conditions. Moisture profiles, ground heat flux and soil evaporation are also calculated. An experiment using a tube of moist sand heated by a radiant heater over a 30 min period to simulate fire conditions was used to test the model. A further test was imposed using experimental grass fire data from the literature. In all cases deviations between observed and calculated results were small.