The present invention provides a luminaire system capable of generating light of a desired chromaticity and luminous flux output during continuous operation with varying ambient operating temperature. The luminaire system can be further capable of maintaining a desired correlated colour temperature during dimming of the luminaire. The luminaire system comprises one or more arrays of light-emitting elements for generating light with a current driver system coupled thereto for selectively supplying electrical drive current to each of the arrays, wherein the current driver system is responsive to drive signals received from a controller. The luminaire system further comprises an optical sensor system for generating optical signals representative of chromaticity and luminous flux output of the light. A heat sensing system is operatively coupled to the one or more arrays for generating signals representative of the junction temperatures of arrays of light-emitting elements during operation. The luminaire system further comprises a controller that is operatively connected to the current driver system, the optical sensor system and the heat sensing system for receiving the signals generated by each of these systems and is configured to generate one or more drive signals for transmission to the current driver system in response to the optical signals and thermal signals received from the optical system and the heat sensing system, respectively, thereby enabling a desired level of control of the output light.