Simultaneous movement of water, vapor and heat in the vadose zone of arid or semi-arid regions is of great interest in evaluating water and energy balance of subsurface environments. Although it is well known that water and/or vapor flow and heat transport processes are closely coupled and strongly affect each other, their simultaneous interactions are rarely considered. In this study, we implemented in the HYDRUS-1D code the coupled movement of water, vapor, and heat in the subsurface, as well as interactions of these subsurface processes with the energy balance at the soil surface. Movement of both liquid water and water vapor in the subsurface can be driven by either the pressure head (isothermal transport) or temperature (thermal transport) gradients. The heat transport module considers movement of soil heat by (a) conduction, (b) convection of sensible heat by water flow, (c) transfer of latent heat by diffusion of water vapor, and (d) transfer of sensible heat by diffusion of water vapor. Simultaneous water flow and heat transport are coupled not only in the subsurface but also by the surface boundary conditions. The code allows a very flexible way of using various meteorological data (daily, hourly, other time intervals) at the soil-atmosphere interface for evaluating surface water and energy balance. The coupled model is evaluated using field soil temperature and water content data from different depths collected at the University of California Agricultural Experimental Station in Riverside, California, during the fall of 1995. Soil temperatures and water contents in three different depths (2, 7, and 12 cm) were simulated using the measured soil hydraulic properties, estimated thermal properties, applied irrigation fluxes, and estimated net radiation as an input of energy at the soil surface over a period of 15 days. Simulated temperatures and water contents closely agreed with measured values.