Caster with Elemental Affinity cast Elemental Weapon, it adds damage?

@mikemearls @JeremyECrawford MC-Sorcerer with the right Elemental Affinity cast Elemental Weapon, it adds damage (every hit/once/never)?

— TJA (@Nay_a_no_mi) May 12, 2016

Elemental Affinity has no effect on Elemental Weapon. If a DM allows it, it should apply to only one roll. #DnD https://t.co/eK3qHoHzWX

— Jeremy Crawford (@JeremyECrawford) June 16, 2016