I would still disagree about the rocks. Water has the second highest specific heat of any substance next to liquid ammonia. That's why areas near large bodies of water like the ocean or the great lakes have mild winters. The water takes a very long time to cool. Conversely, areas without this and only bedrock at a similar latitude can become incredibly cold. Western NY near Lake Erie remains relatively mild during the winter (aside from lake effect snow), whereas central NY can get much much colder without a large body of water.