Freezing rain is the name given to rain that falls when surface temperatures are below freezing. Unlike rain and snow mixed, ice pellets, or hail, freezing rain is made entirely of liquid droplets. The raindrops become supercooled while passing through a sub-freezing layer of air many hundreds of feet above the surface, and then freeze upon impact with any object they encounter. The resulting ice, called glaze, can accumulate to a thickness of several centimeters. The METAR code for freezing rain is FZRA.

A storm that produces a significant thickness of glaze ice from freezing rain is often referred to as an "ice storm". Freezing rain is notorious for causing travel problems on roadways, breaking tree limbs, and downing power lines. It is also known for being extremely dangerous to aircraft since the ice can effectively 'remould' the shape of the airfoil and flight control surfaces. (See atmospheric icing.)

Usually freezing rain is associated with the approach of a warm front when cold air, at or below freezing temperature, is trapped in the lower levels of the atmosphere as warmth streams in aloft. This happens, for instance, when a low pressure system moves from the Mississippi River Valley toward the Appalachian Mountains and the Saint Lawrence River Valley of North America, in the cold season, and there is a strong high pressure system sitting further east. The warm air from the Gulf of Mexico is often the fuel for freezing precipitation.