I would dress him warm in case it is cold and you stay the whole game. I took my little guy to a game in Oct when he was like 7 (He is now 30) and I bought a bunch of the Hot Hands warmers and stuffed them in his pockets, coat, wherever I could and he was warm. He turned out to be hard core VOL. My pride and joy.
Funny thing though-I never really notice the cold when the Vols are doing well. The crowd is going and all the body heat adds ten or more degrees
It's experiences like Saturday of sitting there watching an execution when Neyland seems like a freezer.