That really depends on late Nov-early Dec temps, and snow cover. Last year we had so much snow early, that frost wasn't an issue either. It's not an uncommon thing. When you have sd's into neg temps overnight more regular, the frost goes deeper quicker, unless the snowpack is robust. There may be some frost in the wooded areas, but temps, and lack of snow cover this year probably have kept the frost from going down much. And I wouldn't be out on any ice today.