dress for August wedding

[TNPhiMu]

Ok, so my husband is in the wedding of one of the guys who was his groomsman in our wedding in May. We are good friends with the couple, so we'll be around all weekend for the festivities. Unfortunately, they are OUT OF THEIR MINDS because the wedding is August 5th and the reception will be outside in late afternoon in MISSISSIPPI. In other words, the hottest/ most humid place on earth.

Does anyone have any suggestions on what i should wear? I want something that I can be *somewhat* (cause I know I'll be melting no matter what) cool in the entire day. But, I feel like since my husband is part of the bridal party, I need to have something kinda dressy(more than just a sundress). So, any thoughts(especially thoughts that have pictures attached) would be MUCH appreciated!