An electric radiant heater has a proximity sensor capable of detecting the presence of an object proximate the top surface of the heater's housing. The heater also has a temperature sensor capable of sensing ambient temperature proximate the top surface of the heater's housing. A microcontroller is coupled to the proximity and temperature sensors. Upon the detection of an object atop the heater's housing, the microcontroller determines if the temperature sensor's output is indicative of the presence of ice or snow. If so, a heating element of the heater is allowed to remain in operation. Otherwise, the detected object is considered to be potentially combustible material, and the heating element is switched off by the microcontroller.