From a comment:

For the backstory, as you can see, it is pouring rain. Bush is told not to perform as it is a safety hazard. The rest of the band sits it out but Gavin says something to the effect of screw it, the fans are in the rain, I can be too. We as fans are given one of the most touching, visceral, powerfully raw performances ever, simply because he loved the fans as much as they loved him.

He did tell us not to let the days go by.