Black Ice (or glare ice) is ice frozen without many air bubbles trapped inside, making it highly transparent. This type of ice appears in the color of the material beneath it, often wet asphalt or a darkened pond. Because it may be difficult to detect, it presents a significant hazard to automotive traffic, pedestrians, and sailors.

Black ice, also known as "glare ice" or "clear ice," typically refers to a thin coating of glazed ice on a surface, often a roadway. While not truly black, it is transparent, allowing the usually-black asphalt/macadam roadway to be seen through it, hence the term. It is unusually slick compared to other forms of roadway ice, and is a factor in some car accidents.

Because it contains relatively little entrapped air in the form of bubbles, black ice is highly transparent and thus difficult to see (as compared to snow, frozen slush). In addition, it often is interleaved with wet road, which is identical in appearance. For this reason it is especially hazardous when driving or walking on affected surfaces.

Bridges and overpasses can be especially dangerous. Black ice forms first on bridges and overpasses because air can circulate both above and below the surface of the elevated roadway, causing the pavement temperature to drop more rapidly. Road warning signs with the advisory "Bridge May Be Icy" often indicate potentially dangerous roadways.

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