I fly fish for carp during the hot weather, I'm located in So Cal and have had luck with hare's ear nymphs, carp candy and like said before here, they will go for anything trout like. Catching carp on the fly is rewarding and a half but it is a patience game. Unfortunately if there is no carp, there is no game because it's not very likely that you will catch a carp blind casting but then again I did catch one blind casting a # 10 crappy candy fly.
Your best chance to catch one with whatever you throw is when they are tailing or eating from the surface.
Best of luck.
Martin