Grab a poncho and go. The only potential issue I see is lightning, if that is in the forecast - they stopped Clyde and Seymour in the middle of the show when we were there. Manta and Kraken might be down as well, but many things are under cover - Wild Arctic, Penguins, Turtle Trek, shows (no lightning), etc.
And as always - that might be an 80% chance of Florida rain - 15-20 minute rain in afternoon quickly followed by sunshine and humidity. We have been there for some all day soakers - but they have been some of our best days. Poncho up, and enjoy the limited crowds!