Obviously the colder the better for hanging. We ususally hang our deer for at least 24 hrs(preferably 2-3 days if possible), unless its real warm (like over 65). Then I just go ahead and butcher and get em on ice. The key is to get it cooled down as quick as possible(throw a bag of ice in the chest cavity if you need to), and hang it in the shade. You have to remember, once it cools down, and the temps drop down to 35-40 at night...that meat is cooled down big time. Even if it gets to 65 the next day...it ain' t gonna spoil. Another thing I do is leave the hide on. Once you get the deer cooled all the way down, the hide will actually act as an insulator and keep the meat cool longer. We' ve hung many a deer over the years in 50 degree weather with no problems at all. Just make sure they are in the shade. If you are at all concerned....go ahead an butcher it. Just my .02