It all depends on the deer. My neighbor breeds whitetails and often trades his deer with alot of other breeders in this part of the state. All of his deer will drop their antlers within 3 days of a certain date every year no matter what the weather conditions. I have seen numerous deer around here hold their antlers until april. These same deer still have their anters in april the following year even though it has been a much colder and harsher winter. I think every area is different.