Unprecedented high-temperature operational stability of interfacial silicide-free ultraviolet-A multiple-quantum- disk AlGaN nanowire-based light-emitting diodes on metal is achieved and investigated. Reasonable variations in device operational parameters across a wide range of temperatures demonstrate the high quality of the layer interfaces and efficient carrier injection. We previously presented ultraviolet-A quantum-confined AlxGa1-xN/AlyGa1-yN nanowire-based light-emitting diodes and studied their steady-state electro- and photo- luminescent characteristics at room temperature. Herein, we significantly expand the scope of our previous work by investigating the operational stability of the device across a wide range of temperatures (-50-100°C) with conformal parylene-C deposition, forming a nanowire forest as a polymer/nanowire three-dimensional composite material. This work constitutes part of a larger study into the operational stability of ultraviolet light-emitting diode chemical sensors at a wide range of temperatures for operation in harsh environments such as in downhole oil exploration.