Donna Molnar, 55, set off from home in Ancaster, Ontario, on Friday but her car got stuck in a field of snow drifts.
The vehicle was found a day later, abandoned by the side of a road, Sky News reported.
By this time, fears for her survival were mounting and it was not until Monday, when police officer Ray Lau was trudging through almost knee-high snow, that his dog Ace picked up the woman's scent.
Officer Lau was stunned to find Molnar still breathing. Molnar was wearing a simple winter jacket and she had been buried in snow just a few hundred yards from where her car had been found.
Police believe the snow's insulating effect was what kept her alive. "That's a Christmasmiracle. Sometimes the good don't die young," he said.