Black ice is treacherous and nearly invisible, and along with its winter companions, snow and slush, it causes over 100,000 vehicle accident injuries every year. While black ice is a common winter foe for drivers, you can learn how to forecast, detect, and avoid it by using a sensible winter weather awareness strategy.
What Is Black Ice?
Winter conditions bring a variety of perils to our roadways, including sleet, snow, fog, freezing rain, and black ice. Black ice is not actually black; it’s called that because it is transparent and therefore shows the color of the pavement underneath (that is typically black). It visually blends in with the road because it is composed of a very thin frozen layer — sometimes just a hundredth of an inch thick — making it almost impossible to see but allowing it to still be super slippery. That’s what makes it so dangerous.
How Does Black Ice Form?
Black ice forms when a very thin layer of water freezes on a roadway or other paved surface. Like regular ice, black ice requires temperatures of 32 °F (0 °C) or less to form. Freezing drizzle or freezing fog are usually responsible for the formation of black ice, rather than heavy precipitation, because the smaller amounts of water stick to roadways and freeze much faster. Black ice may also develop when snow or ice melt and refreeze on the pavement, which usually occurs overnight during colder temperatures.
Forecasting Black Ice
Black ice is stealthy, so it's a good idea to have some tools on hand that can help you stay ahead of slippery winter driving conditions. A good place to start is with your personal home weather station. Temperature, humidity, and precipitation patterns often vary across a city or county, so having accurate information about your neighborhood weather offers the best precision to pinpoint the potential for black ice. For instance, use the AcuRite Atlas® home weather station to track hourly temperature changes to estimate when the ice on the roads has melted. You’ll also want to monitor local TV or internet sources, as conditions frequently change with winter weather systems. Here are a few points to check for the possibility of black ice.
Is Moisture Expected?
A forecast of freezing drizzle or freezing fog means there is a significant threat of black ice. Nonfrozen fog may also cause black ice if temperatures are barely above freezing. If there’s melting snow or ice that is expected to refreeze, you can bet some black ice will be in the mix.
Are Freezing Temperatures Expected?
Since black ice cannot occur without freezing temperatures, this is an easy one. Remember, temperatures can vary; check your temperature data in real-time with the My AcuRite® app or website for best results. Beware: It may be a degree or two colder at the ground than a thermometer shows because cold air sinks and a thermometer is several feet above the ground. This is true for any weather-station thermometer, whether it’s at the airport or in your backyard, but the temperature in your backyard will be a better representation of the local road conditions in your area.
How Warm Are the Roads?
If you’ve had a recent warm spell, it will take longer for the pavement to cool enough for black ice to accumulate. You can monitor the temperature trends from your weather station anywhere with My AcuRite. Use the display to see how long it’s been below freezing. It usually takes a few hours of below-freezing temperatures before black ice will stick. Snow is different in the way it sticks to roads because heavy snow will quickly cool the roadway even after a fairly warm day, so it will begin to accumulate sooner.
6 Black Ice Driving Tips
Winter weather driving, be it in snow or ice, requires patience and diligence. If you get in a hurry, you’re going to get in trouble, but there’s more to black-ice safety than reducing your driving speed.
- Check temperatures before leaving home to verify whether black ice is possible. You don’t want to create a hazard to other motorists by driving very slowly when there’s no reason to do so.
- Watch out on bridges — they freeze first, so a slip-free road might give you a false sense of security.
- Avoid sudden lane changes, turns, or braking.
- Drive below the speed limit, especially on hills.
- Consider traveling at a later time to allow morning temperatures to rise, as one or two hours can make a huge difference in driving conditions.
- Do you see lots of accidents along the roadway? That’s a pretty big clue!
Give Black Ice the Cold Shoulder
Black ice is a special class of hidden winter driving danger, but it’s possible to avoid. Your black ice safety tool chest should include the best weather information from an AcuRite weather station so you can stay ahead of slippery conditions and take sensible driving precautions. Take care and stay warm!
Steve LaNore is a certified broadcast meteorologist with more than 30 years’ forecasting and technical experience. He has provided meteorological consulting for everything from insurance adjusters to court cases and is a nine-time award-winning author and broadcaster. LaNore has authored two books, available on Amazon. He resides in north Texas near beautiful Lake Texoma.