This might seem like a silly question...

But my son is almost 6 months old and fairly big for his age. People have given him tons of clothes as gifts and hand me downs. I'm so grateful for all them, and was looking forward to him growing into some of the bigger ones. Problem is, we live in a very cold climate and he has been living in long sleeve onesies and thick layers for several weeks now. Are all the short sleeve onesies going to go unused? Is there a way to use them in cold weather that I might be overlooking? He'll be way too big by the time the weather warms up again, and I want to get good use out of his clothes!