But -1 doesn't mean that. A myriad of factors comes into play before you can tell if there will be ice on the road, not least the temperature of the road it sel

But -1 doesn't mean that. A myriad of factors comes into play before you can tell if there will be ice on the road, not least the temperature of the road it self. It takes prolonged periods of cold to chill a road down to where it can sustain ice. Conversely, after a night with hard freezing, ice can remain on the road for hours, even as temperatures climb into decidedly balmy territory. In Denmark people rely on weather forecast warnings on the radio for this more than intuitive reading of the thermometer.