Probably likely that you don't really need one if you seal up the exterior sheathing and take the ADA (Airtight Drywall Approach) on the interior.
If you have something where you be concerned about a vapor push from the exterior, might make sense to have some rigid foam at the outside wall to help mitigate that push. That being said, this can create other condensation potential if not done properly.
Gary is the psychrometric chart chart wiz.
The exterior there is plywood sheathing, and tar paper (siding coming soon). We don't really get that cold here, but we do get some wind, especially against that wall.