High intensity focused ultrasound (HIFU) can noninvasively induce thermal coagulation in cancerous tissue. An adequate increase in temperature and an appropriate duration is critical for such thermally induced damage. The aim of this study was to provide a model pertinent to temperature monitoring based on ultrasound imaging in HIFU procedure. A two-dimensional model for temperature estimation based on the linear thermodynamic properties of biological tissues is addressed. To measure temperature changes in the focal zone, we proposed an algorithm using a lateral speckle tracking technique. A modified cross correlation algorithm with a synthetic lateral phase was developed to reduce the computation required allowing for real-time implementation. Using this method, the expected minimum measurable temperature change was approximately 3°C with a resolution of 5 mm in the axial direction and 2 mm in the lateral direction. It is believed that this model is a useful tool for the monitoring of temperature in HIFU.