Originally Posted by Saddlebag
If your horse is already growing a good winter coat then you will do him more harm than good by blanketing. Just because you feel chilly don't go thinking your horse is. Blanketing takes away his ability to regulate his body temperature and horses often overheat under a blanket. Even a sheet can mess up his thermo regulator. He doesn't need to be in a barn as long as he can get up against a wall which horses prefer.
You are correct on this, especially the overheating part. Also, if the blanket is put on to early then they will not grow a coat thick enough to withstand the weather.
I am assuming that your post was directed twards mine. The BO only has the blanket rule so when the weather turns real cold (neg. Temps.) they can have blankets on at night to supplement their coat.