Quote Originally Posted by danielxcutter View Post
(emphasis mine)

To be fair, I didn't notice the "if struck no saving throw against the fire damage" clause until now.
Like I said, it'd be up to the DM I guess, but personally I feel if something explodes on impact at skin level you were "struck" by it. It's D&D but any vague correlation to real world physics would lead to that result too. If the impact happens at ground zero on your body...