This paper presents a novel technique to estimate the temperature distribution of a milling tool during machining. In this study, heat generation during the machining process is estimated using cutting forces. We consider the heat to be time-dependent heat flux into the tool. In the proposed model, we discretize each rake face on a mill into several elements; each experiences time-dependent heat flux. Second, we calculate the time-dependent heat flux as several constant heat input starts at different time. Finally, we sum the temperature rise from each heat flux to obtain the overall temperature change. A similar concept is applied on the flank surface, where the flank wear area is modeled as an additional heat generation zone. Experimental results are presented to validate the developed model.