I can remember a little rain at Wrestlemania 24, but it wasn't anything serious, and there was a canopy over the ring.
I've been going to Sun Life Stadium for years (back when it was still called Joe Robbie Stadium). I've seen my fair share of Dolphins and Marlins games, and I can tell you the weather is MUCH worse during the seasons for both of these teams, especially the Marlins. Severe lighting storms, heavy rainstorms, and there's always the rare possibility of a hurricane warning. It can be a real mess, but I don't expect anything serious next Sunday. I've seen the weather reports, and there might be a light drizzle, but I don't think we'll see any hard rainstorms, that could ruin the show. I'm sure WWE has thought of this, and they will take the necessary steps (there has to be some sort of canopy over the ring) to prevent rain from ruining the show, so the weather shouldn't be a problem.
But it doesn't matter for me. I'm going to Wrestlemania 28. I will be there live, and the weather won't bother me one bit. I've sat through Dolphins games, that featured a lot of rain, and if there wasn't any lighting around, I would sit around in the stands during Marlins games during rain delays (of course I was wearing a poncho or raincoat). Rain won't ruin my experience, and I will continue to hold down my seat in the stands regardless of the weather situation.