Yup, the cold is cold on the deer too. They'll move when the temps are warmer to conserve body heat and energy. Look for them at mid day or the warmer part of the afternoon. You have to sacrifice the scent bit a little when it's fridgid. Do the chemical packs and all that. I have some inserts that you put chemical heaters in place in your boots. It really helps to keep the trunk and the feet warm as well as the head. Balclavas are a necessity and sometimes I double them. Sims rubber wraps on bowhandles are helpful. Do isometrics and pull the bow every half hour or so.