The woman was slaloming with her son when she stopped at a particularly icy and steep part of the piste to take off her skis. She is thought to have lost her balance on the slope and slid into a tree. Her son found her but police say he did not see the accident happen.
Another person was found dead on Saturday morning on a slalom piste in the Norefjell ski resort, south of Hemsedal.
There were no witnesses.