An electronic system, or its battery thermal management system, determines a thermal state of a battery used in the electronic system. A temperature at a position proximate the battery's cell is sensed during operation of the electronic system to produce a sensed value. Additionally, a temperature offset value is determined based on an aging factor for the battery. The sensed value is then adjusted based on the offset value to produce an adjusted value representative of the thermal state of the battery. According to one embodiment, a relationship between temperature offset value and battery aging factor is prestored in a memory of the electronic system. In such a case, the offset value may be retrieved from memory periodically or in response to a trigger event based on a determined aging factor. According to another embodiment, the offset value may be computed in real time based on a determined aging factor.