The maximum machining speed in milling processes is significantly limited by the upper temperature limit of the materials of the tools used. During the cutting process, large heat fluxes occur at the cutting edge of the tool, resulting in short term temperature peaks. The precise measurement of these temperature peaks is very challenging, due to their highly transient nature and limited spatial accessibility. Analytical and numerical simulations are therefore a suitable tool to determine the thermal load on the milling cutter. Current FEM modeling approaches for machining processes often require substantial computational resources, resulting in significant CPU time and memory usage. Therefore, the aim of this work is to develop a fast and computationally efficient simulation approach to predict transient tool temperatures, with a focus on the accurate identification of temperature peaks. In a previous study, a coupled approach was used to determine the heat fluxes at the cutting edge caused by the milling cutter’s engagement in the workpiece. For this purpose, an FEM machining simulation of the milling process was combined with a simpler heat conduction simulation of the cutter. The heat fluxes then served as boundary conditions in the heat conduction simulation to calculate the resulting temperature field. In this approach, a spatially and temporally constant geometry engagement and thus a spatially and temporally constant heat flux into the cutting edge has been taken into account up to now. In the present work, the temporally and spatially varying nature of the cutting edge heat flux is considered and its influence on the resulting temperature field and especially the maximum temperature of the tool is investigated. The results of the extended thermal simulation model are presented and compared with the results of the previous work.