Weather Explainers

Black Ice: What Is It, And Why Is It So Dangerous For Drivers?

Black ice is a thin coat of highly transparent ice. It is difficult to see, especially at night, and can bring hazardous driving conditions.

Black Ice Is Dangerous, Here’s Why

When winter starts, people start worrying a ton about black ice.

And for good reason.

Black ice can be very dangerous, so it's important to know what it is and how you should react if you have an encounter.

Let's start with the basics. Black ice is a thin coat of highly transparent ice.

It blends in with road pavements since it is so thin, making it nearly impossible to see. It's called "black ice" since it looks black, like the color of the road pavement it forms on.

(MORE: When is the Coldest Time of the Year?)

This is an example of black ice on a dark roadway.
(Getty Images)

What Causes Black Ice?

If the temperature rises above freezing or the sun comes out during the day, any snow on the ground will slowly melt and cause road surfaces to become wet. This is also possible if it rains, which could also lead to wet roadways with some puddles.

Then, as the temperature drops below freezing with the sun setting on a still-wet ground, black ice will likely form on paved surfaces due to the refreezing.

Black ice can also form if moisture in the air condenses and forms dew or fog, and then the temperature drops below freezing. The latter is called freezing fog.

A visual demonstration of how black ice forms. Snow melts during the day as temperatures rise above freezing and lead to water on roads. When temperatures drop back below freezing, usually at night, any water on roads freezes into black ice.

Watch out for the most common locations black ice forms: including bridges, overpasses and spots on the road shaded by trees or other objects.

Bridges and overpasses are prone to black ice because cold air is able to flow underneath the road surface, which lowers the pavement temperature. Shaded spots on the road are prone since they receive less warmth from the sun during the day.

(MORE: Black Ice And Driving)

Why Is Black Ice So Dangerous?

Since black ice is highly transparent, you won't be able to see it while driving down the road.

Roadways become very slippery when black ice forms, leading to hazardous driving conditions and an increased risk of car accidents.

(MORE: Weather-Related Car Accidents Far More Deadly Than Tornadoes, Hurricanes, Floods)

Here are a few tips that may help if you get caught in areas of black ice:

Keep your steering wheel straight. If you turn the wheel, you have a better chance of sliding and losing control of your vehicle.
Do not brake. Braking causes the vehicle to slide, especially if you brake too hard.
Take your foot off the accelerator to reduce speed. It is best to let the car stop on its own if you have enough room in front of you.

Rob Shackelford is a meteorologist and climate scientist at weather.com. He received his undergraduate and master’s degrees from the University of Georgia studying meteorology and experimenting with alternative hurricane forecasting tools.