Hi all. I'm relatively new at decorating for money. I have an order for late July for a cake that will be kept outdoors.  I need to use modeling chocolate or fondant on this cake. What is the best in heat and do you have any suggestions on how to keep it from melting?

I'm not sure about the fondant melting, not sure if it can.  However, if you're going to crumb coat with BC, don't use butter, shortening only. 

I made 100s of b'cream cakes in hot weather and as far as I know none of them melted.  I figure weather in IL will be not only hot but very humid  (I lived in northern IN) which might present a problem.  Be sure to advise your client to set up the cake table in shade and try to set it up no more than an hour before the start of the event.

Fondant should not give you  any problems.  I never used modeling chocolate to cover a cake.

AHa! Welcome to my life. I mean that in the nicest possible way :) I live in a tropical climate (Darwin Australia) and it is HOT here. For a cake sitting outdoors in the shade (I would never let a cake sit in the sun) I use regular buttercream (American buttercream) or I would use fondant. Things melt fast. So that cake would be super chilled (at least overnight). No modelling chocolate or meringue buttercreams. Use the most stable mediums you have available to you. And chill, chill, chill!

I had made two cakes for a family event a couple of summers ago, one was fondant and the other was a three tier butter cream with edible pictures all over each layer.  It was in the 90's that day.  They were shaded and and sat out for awhile.  No problem, just make sure any buttercream you use is made with shortening only, or grab some buckets of Wilton bc.  It should be fine.

ASomeone else from Darwin...yay! Have you used modelling chocolate here? I just made a batch to see how it goes....