TRUCKEE (AP) — The ice on Donner Lake in the Sierra Nevada may look sturdy, but authorities say it is unstable and are warning skaters of the dangers.

Fire and rescue officials in Truckee say while it was bitterly cold over the past month, temperatures have warmed and the ice is fragile.

They say conditions are similar to five years ago when a skater fell through the ice and drowned.

Authorities say there’s no law or ordinance prohibiting ice skating, but they are urging people to weigh the risk before lacing up their skates and heading onto the lake.

(Copyright 2013 The Associated Press.)