Weather Explainers

Weather Words: Candle Ice

Candle ice is late-season ice that weakens from the inside as warming temperatures cause it to break into fragile, vertical columns, making it unsafe despite often appearing solid.

How Is Candle Ice Formed?

Candle ice is a late-season ice phenomenon that signals winter is losing its grip. As temperatures rise and sunlight grows stronger, ice on lakes and rivers begins to deteriorate from the inside rather than melting smoothly from the surface.

The ice separates into vertical, candle-like columns, giving it a honeycombed appearance that may still look solid at a glance.

This structure forms as meltwater drains between individual ice crystals, weakening the bonds that once held the ice together. Despite its appearance, candle ice has very little strength and can fail suddenly under weight, making it especially dangerous for people who venture onto ice in early spring.

For meteorologists, candle ice is a clear visual cue that ice season is ending and waterways are transitioning toward breakup and open water.

Candle ice on a lake in winter.
(Getty Images)

Jennifer Gray is a weather and climate writer for weather.com. She has been covering some of the world's biggest weather and climate stories for the last two decades.