ORIGINAL: BTBowhunter
Never seen any studies on this but I've heard and read that It's all about the bucks testosterone levels. Cold weather supposedly has nothing to do with it. Typically if there are does still coming into estrous in the area, teatosterone levels will tend to stay higher and most of the bucks will keep their horns. I know that in areas where the doe fawns are healthy and have enough body weight, they van extend the secondary rut a bit and therefore the bucks keep their antlers a bit longer.
Some experts claim the exact opposite. They say that after the peak of the rut testosterone levels in dominant buck drop rapidly leading to early shedding. They also claim that the stress of rutting by dominant buck also contributes to early shedding.