This costume is adorable! It was light but warm. I think it requires at least a long sleeve shirt as well. It fit my 11-month-old son at 22 lb. As I did, I would suggest giving it a "test run" first because it took my son a little while to get used to the hooded part. The hood has an inner lining that Velcros, but I found that it fit better on his head and looked more like a peanut without closing that inner part. I highly recommend this costume.