Tony,
I can catch CNBG all winter long where my feeder is located. I have to wait a little longer and sometimes set the bait a little lower in the water column, but I can catch them. The last time I was out at the farm the water temp was in the mid 40's to low 50's depending on where in the pond I was fishing.
With all that said, my big pond is a bit bigger than most and I do have a lot of water, so that might change things a bit. As for ice, there has been some, but not much more than just around the edges.
