I made a wedding cake this weekend and it was beautiful, but as soon as I had to deliver it the client I began to worry. It was the hottest day of the year so far, at 104 dgrees. I started the van and ran the AC for over 15 mins and then started to load the cake. I only had to take the cake 10 mins away and half way there the buttercream started to slid down the sides of the cake. I started to freak out. When I arrived at the location I had to scrap off the dark chocolate scroll work and reapply the buttercream and scroll work. The locations AC was bearly working and even after I fixed it I still don't think I was going to hold up until cake ceremony time. I felt horrible. I know I don't control the weather, but I never experienced something like this. Does anyone have suggestions for high heat cake designs? Is fondant better than buttercream in high heat? Has this happened to anyone before?
indydebi has a great BC recipe that holds up well in heat and high humidity. BC with butter in it will never hold up. Her recipe is in the recipe section of this site.
For summer months i use more shortening and less butter in my butter cream. I don't normally have to many days that are as warm as you are describing. But i also, refrigerate the cake at home. So when i deliver its cold and more solid, it makes for an easier delivery, And i tell everyone that orders a cake for an outside wedding that sugar and butter will melt there is no changing the laws of physics, it is what it is, butter cream in the heat of summer will melt and if the bugs land on it, well odds are they aren't taking off.