I stand corrected, memory getting dim on detail issues. This makes sense as the thermal mass of water could not have formed 8" on Gardner overnight if the difference was only two degrees instead of 7 degrees.

I cautionary note, if you will be venturing onto flash frozen ice you will not be able to tell how thick the ice is and beware of spring water spots where the ice will be thinner. That day on Gardner lake the 8" ice was completely invisible. With full sunshine the experience was surreal. We were walking on glass, water absolutely clear, every detail on the bottom clear as we walked over deeper water. We chopped at the ice with a spud every 25 feet or so to confirm the ice was safe on the way out.