Abstract: A method and apparatus for advance warning signaling to a motorist of an ice condition on a driving surface. The method steps include mounting a plurality of traffic signalling devices along a driving surface for sensing the prevailing temperatures and thereby continuously signal a motor vehicle operator of the changes in temperature as he approaches a driving surface subject to freezing to permit him to take any necessary precautionary corrective action in driving the motor vehicle. The signalling devices utilize thermostat elements for sensing a narrow temperature range adjacent the freezing temperature and provide visible signals, preferably two colors for signalling a warm or nonhazardous temperature, a cold temperature signalling a frozen driving surface or a combination or mixture of the colored signals to permit the motor vehicle operator to be warned, in advance, as he approaches a driving surface that is becoming colder, leading to a stretch of a driving surface that may be frozen.