We have one rule about clothing...IT MUST BE WORN!
Really, whatever you want to wear is fine by us. I always tell "my" brides that the more comfortable you are the better the pictures will be. I can't tell you how many times we've done an outdoor wedding in the colder months and the bride is in a sleeveless sheer gown that leaves her in goose flesh and shivering through her vows. I don't need to tell you that we can't get a ton of photos in that situation. I can guarantee you that if that bride had worn blue jeans and a cute jacket or sweater we would have gotten TONS more pictures.
So what if you really want to wear that "to die for" gown in the middle of February? There are some simple things you can do to make your wedding more comfortable. Wear hose, silk long johns (available at Walmart), and pick up a nice shawl or wrap to throw over your shoulders in between photos.
Of course this is the south, so what if you want your groom to wear a tuxedo in the middle of July? If you don't want all the pictures from your wedding to be sweat-stained you will want to make the tux or suit to be as few pieces as possible (like just skip the vest and cummerbund) or check out Pintrest to see what alternatives to a tux you could consider. You might also think seriously about having your wedding in the late evening, inside your rental cabin (air conditioning) or in a chapel.
One other possibility is to have your wedding at our waterfall location, Serenity Falls. Usually beside the waterfall is about 10 degrees cooler than the surrounding area, much nicer in the summer (a bit bracing in the winter, but then just pick up the silk long johns!)