Having lived and kited on the OBX, I second Evan’s comment about Kitty Hawk Kites. The OBX is probably the safest and best location to learn to kite in the U.S. Chris Moore from Kitty Hawk Kites and his instructors will treat you very well. Personally, I can recommend either Will Brooks or John Gates as instructors from KHK. The air and water temps in mid July will be pretty warm. Winds are lighter than in the spring, but less gusty too.
Chris has a package set up now that is a great deal. If you buy a kite and board combo, you get a free three hour private lesson. Sounds like a great way to get your son set up with a new kite and board as well.