Freezing rain

Freezing rain is liquid precipitation that falls through subfreezing air near the ground and freezes on contact with exposed surfaces, forming a coating of glaze ice.

Freezing rain is liquid precipitation that freezes on contact with cold surfaces, forming a layer of glaze ice. It is a common winter hazard in Canada, distinct from sleet because the droplets stay liquid until they hit the ground.

What it is

Freezing rain is rain that remains liquid while falling through subfreezing air near the surface. The droplets are supercooled, meaning they stay liquid below 0°C, and freeze instantly when they hit exposed surfaces like roads, trees, or power lines. The result is a smooth, transparent coating called glaze ice.

Why it matters

Freezing rain creates hazardous travel conditions, including slippery roads and sidewalks, and can damage infrastructure. Significant accumulation, often called an ice storm, can weigh down tree limbs and power lines, leading to widespread outages. In Canada, it is a notable winter hazard, especially during storms that affect cities like Vancouver.

Key details

Freezing rain forms when snow melts in a warm layer aloft and then falls through a shallow cold layer near the ground. It is different from sleet, which freezes into ice pellets before reaching the surface. The METAR code for freezing rain is FZRA.