Abstract: A high-temperature warning indicator is provided for attachment to a firefighter's helmet. In a preferred embodiment of the invention, the indicator is in the form of a dual-color LED mounted in the tip of a highly insulated, lightweight housing. A microprocessor located within the housing and coupled to a temperature sensor activates the light, changes it from solid to flashing modes, and changes the color of the light as various temperature/time thresholds are reached. A clamp or similar mounting device is provided for securing the device to the brim of the firefighter's helmet.