It rained nearly the whole time we were at USF last week. Not thunderstorms, just constant drizzle. As far as I could tell, nothing closed during the rain. I could be wrong about this, but I don't remember anything being closed. I know some things shut down during thunderstorms with lightening, but we didn't experience that. And, the last day we were there the sun came out and it got reeeeaaallly hot so we realized that clouds and drizzle weren't really a bad thing after all. Just take a poncho and go for it. At Universal Studios, most everything is inside anyway so you only have to be in the rain going from place to place. Earl, CoasterFEV and IOAtech can speak to what, if anything, closes during rain better than I can.
Nan