It's really no hotter here than it is in many other parts of the country during the summer. The difference is that people in other areas don't spend hours walking around on cement that is soaking up the heat. It feels much hotter in the theme parks than it feels outside the parks.
Normally, we have afternoon thunderstorms as a result of the collision of the sea breezes over central Florida. The storms come up fast and can be quite severe, but usually don't last long. Lately, we've been in a very dry pattern. Unless things change (which is not predicted), we will have fewer summer storms. That's not good. We really need the rain. We have already had a ton of brush-fires in the area.
OP, since you are not used to Florida during the summer, please be careful if there should be a thunderstorm. Lightening is a very real danger. Each year, multiple people are struck by lightening. When lightening starts, locals take cover. It always amazes me then number of visitors I see walking around in intense thunderstorms as if they are immune to the danger.