Due to the restrictions of a car's thermometers, the best way to know if roads are icy before heading out the door is to be aware of when, where and how black ice forms. The prime times for the development of this ice are around dawn and in the late evening, when temperatures are typically the lowest.
http://www.accuweather.com/en/weather-news/black-ice-driving-dangers/22052530
1 While snow is the most common cause of road icing, it is freezing rain and freezing drizzle that create the most treacherous and fearsome type of road ice, referred to as 'black ice'.
http://icyroadsafety.com/weather.shtml
Answers. Best Answer: Water starts to freeze at 32 deg Fahrenheit. If the road surface is at or below 32 degrees, you will get freezing. A dark road surface is usually warmer than 32 degrees during the day, because of the solar influence as well as traffic. Heavy cloud cover will prevent solar heating of the road surfaces.
https://answers.yahoo.com/question/index?qid=20100312030137AA3IQQd
Icing of the road is very dangerous to travel. Even a small amount of ice on the road can lead to accidents. The temperature and the amount of precipitation determine how much ice will be on the roads. You have probably heard that ice freezes on the bridges and overpasses first.
http://www.theweatherprediction.com/habyhints/7/
1 Most road ice accidents are caused by snow. 2  It doesn't take much-even a dusting can be enough to make roads treacherous. 3  In fact, the worst outbreaks of accidents happen during very minor snowfall events, rather than during big snowstorms when awareness and preparation levels are greater.
http://icyroadsafety.com/weather.shtml
Black ice forms when the air is at 32 degrees or below at the surface and rain is falling, according to AccuWeather Meteorologist Andrew Mussoline. The ground temperature causes the precipitation to freeze upon impact, thus creating ice. Sleet and the refreezing of snow or water can also generate black ice.
http://www.accuweather.com/en/weather-news/black-ice-driving-dangers/22052530
If the pavement is dry but you are seeing spots of pavement that look dark and glossy, that is probably going to be black ice, Lee said. Before getting on the roads at night, drivers should be informed of the area's weather conditions, as black ice is hardest to see in the dark, according to Lee.
http://www.accuweather.com/en/weather-news/black-ice-driving-dangers/22052530
1 Freezing Rain and Freezing Drizzle. 2  While snow is the most common cause of road icing, it is freezing rain and freezing drizzle that create the most treacherous and fearsome type of road ice, referred to as 'black ice'.
http://icyroadsafety.com/weather.shtml
But as long as the air temps are above freezing and their is snow melt from air temperature and solar heating, you are not likely to have it freezing while their is significant melting. As soon as the temps start to drop though, once the surface of the road gets back down 32 degrees it will start to freeze.
https://answers.yahoo.com/question/index?qid=20100312030137AA3IQQd
1 Freezing Fog. 2  Freezing fog is a less common cause of road icing, similar to freezing rain in its formation. 3  Dense fog is nothing more than tiny water droplets suspended in the air. 4  If temperatures are below freezing, these droplets can begin collecting on road surfaces (especially bridges and overpasses).
http://icyroadsafety.com/weather.shtml
what temp is freezing for the roads
32 degrees is the freezing temperature of the roads.