+1 to the hard water comment. I see you live in FL so there's likely dirty rain and/or salt in your rain that doesn't agree with the wax/sealant that was used on your car. They make special formulas for seaside parked cars.
Personally, i *couldn't* get rid of my water spots until i took a buffer to the whole car and started over half-ass wax job i had been putting into it the last few years. Now that i use a high quality sealer after a buff, and a few coats of wax after a polish no more water spots...