Scott wears long sleeves and pants year round because it's his personal choice. He doesn't NOT have a skin problem. He does NOT have sensory issues. He likes the layered look and a collar with bottons closed up to the neck. If he is comfortable like this, I don't have to worry about covering him in sunscreen. He swims in a surf suit.
When we moved to Georgia (from Florida) when he was three, he wore shorts. It averaged 40 degrees in winter and he would not put on pants ( I had to be careful when we went out). One Winter night I took him and William to Kindermusic. Scott took his close off in the car and cried and insisted he wasn't getting dressed. I wrapped him (naked underneath) in my heavy coat and brought him inside. Finally in Spring, I got him to put on pants and sleeves and he never took them off.