Techniques for estimating the temperature of an external portion of a medical device are described. In an example, processing circuitry may determine a temperature sensed by at least one temperature sensor of an internal portion of the device, and determine, based on an algorithm that incorporates the temperature of the internal portion of the device, an estimated temperature of a second portion of the device, wherein the algorithm is representative of an estimated temperature difference between the first portion of the device and the second portion of the device based at least in part on a dynamic transfer function that operates in a time-domain.