I'm doing a cake for my daughter 8th grade graduation dinner that is outdoors, at a park, what kind of frosting should I use, because the weather is going to be between 83-86 degree's. Will fondant hold up, the cake will be inside a netted tent. Or should I do buttercream.

Fondant holds up better in heat than does buttercream.

I would go with fondant just to be on the safe side. It will withstand heat much better than buttercream.

I've heard reports around here that there is a buttercream recipe that holds up to the heat. That has not been my experience. But fondant will hold up rather well for a short period of time. Keep it in A/C for as long as possible before bringing it out to the heat. It may still be very soft for cutting so be prepared. Basically, cakes have no business being out in the outdoors in summer so keep them inside a more climate controlled area whenever you can.

Indydebi's BC is great in the heat. Here's the link:

http://cakecentral.com/recipes/6992/indydebis-crisco-based-buttercream-icing

If I know its going to be hot and I plan on using buttercream, I have froze the whole cake then it will thaw as it sits out.

thank's everyone