This document describes systems and techniques that use a virtual temperature-sensor for active thermal-control of a lighting system having an array of LEDs. The system and techniques use a forward voltage across the array of LEDs as the virtual temperature-sensor, converting the forward voltage to a level that is detectable by an MCU of the lighting system. In response to determining that the forward voltage exceeds a threshold, the lighting system may reduce an amount of an electrical current provided to the array of LEDs to decrease the forward voltage and alleviate a thermal condition that may be detrimental to the array of LEDs, thereby maintaining luminance capabilities of the array of LEDs and prolonging life of the array of LEDs.