Ordered these just in time to go snow tubing.  All day long on a cold mountain, weather in the teens and twenties, he stayed warm and dry.  I got a 5/6 for my son, and they are the slightest bit large on him, but with his pants underneath and his jacket on top and boots on, they stayed up perfectly.  This in mind, the only thing they are missing is a waist adjuster, because that's where they are big.  Please keep in mind that my son is thin, so if your kid is a little more stocky, they will be fine.  Excellent product, recommend highly.