Not here. It usually gets hotter here after a rainstorm, at least in summer. The humidity goes up so much that its just oppressive.
In the summertime, Miami is the coolest city in mainland Florida, regardless of storms. But yes, the afternoon thunderstorms cool things down a little. All that cold air in the downbursts for one thing, not to mention the cold rain. Standing out in a thunderstorm can be surprisingly chilly.