Finally found a robe roomy enough for my husband.  This robe is not a  size X-large for a growing teen.  It's for a man with some girth around the chest and waist.
Also, I was looking for a fabric that washes well and is suitable for the whole year.  The fabric is cotton with a waffle weave that makes it somewhat insulated for chilly mornings, but you could still wear this robe in warm weather;; it breathes. Navy blue is also a nice looking color especially with the white trim.  Very neat and classy.