Bathing twice a week is a bit much, but as long as you use a very mild shampoo, make sure it gets rinsed all the way out, and make sure your pup is drying out completely after each bath, it's not necessarily a problem either - it's just going to depend on your individual dog's skin and tolerences.
That said, is there a particular reason you need to bathe her that often? I live in Texas (also hot and humid) and bathing dogs doesn't do anything for them EXCEPT when they're actually wet - they don't sweat, so heat doesn't effect how they smell. If you're thinking it would help to keep her cool, you're on the right track, but I would just set up a kiddy pool for her to lay in instead.
