Traditionally, hunters are more likely to be afield during cool weather. They will usually be out in force with the onset of the first weekend norther during the deer season. When there are many observers spending time in the field it is more likely that breeding activity will be noticed. Bucks, like hunters, have a tendency to move around during cool weather. Bucks with hardened antlers are ready to breed and are looking for a willing doe.
More movement means more opportunity to encounter a receptive doe.
This increased movement helps give rise to the idea that cold weather causes the rut. However, this theory is disproved by white-tailed deer breeding in tropical climates. We once thought that late fawning could be a problem in areas where survival was low and antlers were poorly developed. Newly weaned fawns on the range in late fall would have a harder time surviving. A lack of adequate nutrition at this time could affect future body and antler production.