I think they mentioned the weather because it's relevant to his reputation as a legendary live performer and it's part of a great story. [1] There's something almost magical about incredible live performances. I can't really describe it, but sometimes a show has the perfect mix of emotion and artistry and it's completely mesmerizing to be a part of, even as a spectator. Participating in that moment bonds millions of people together in a small way. Even if they have nothing else in common, they were able to experience that together. Prince's Superbowl performance was one of those moments.

[1] http://www.maxim.com/entertainment/prince-2007-super-bowl-pe...