As energy consumption in high-performance systems has increased, thermal management has become a big challenge. Providing a cost-effective and detailed temperature sensing mechanism is crucial to effectively employ a thermal management technique. Existing hardware sensors are too costly to implement and add additional heat while software simulations fail to account for all possible hardware effects.In this paper, we describe a software solution for temperature sensing that uses real hardware resources such as performance counters. The resulting temperature model provides a detailed spatial gradient of the processor and executes at runtime. In particular, the model is configured for the Pentium 4 processor. We run SPEC2000 benchmarks to analyze the thermal behavior of applications and explain the potential benefits of using our model for temperature aware research.