Could be a roof/siding leak, could be a burst pipe, could be a foundation that isn't well-sealed, or could just be built-up humidity in a vacant house.

Well, some of my tenants decided that the air conditioners weren't sufficient - never mind that thousands of us were suffering in the relentless heat and humidity and others were actually dying.

And better than paralizing 80% humidity. 

No mold. the humidity level is a little high. and a moisture barrier is definitely next on the list.

Here is an example:If it's not too humid, the floors should dry in 24 hours (no dryers needed).

I tell you, with this humid Gulf Coast weather you certainly are in the right "environment" for mold investigating and remediation.

With the humidity in Florida, which one is better?

Moisture (especially in humid or waterside locations) always tries to migrate into a conditioned environment.

For the most part Louisiana is much the same as other places I've visited (with the exception of New Orleans) just more water and humidity.

People are friendly, plenty to do outdoors, and the weather is great minus the humidity at times.