Ultrasound brain therapy is currently limited by the strong phase and amplitude aberrations induced by the heterogeneities of the skull. However, the development of aberration correction techniques has made it possible to correct the beam distortion induced by the skull and to produce a sharp focus in the brain. Moreover, using the density of the skull bone that can be obtained with high-resolution CT scans, the corrections needed to produced this sharp focus can be calculated using ultrasound propagation models. We propose a model for computing the temperature elevation in the skull during high intensity focused ultrasound (HIFU) transcranial therapy. Based on CT scans, the wave propagation through the skull is computed with 3D finite difference wave propagation software. The acoustic simulation is combined with a 3D thermal diffusion code and the temperature elevation inside the skull is computed. Finally, the simulation is validated experimentally by measuring the temperature elevation in several locations of the skull.