I am doing my first ever wedding cake for some friends at the end of June. I've got the whole cake planned out for the most part (3 square tiers - 14", 10" and 6" - covered in white chocolate ganache and fondant with a couple gumpaste peonies as decoration) but am concerned about what the weather will be like that day. The reception will be outside in a park with no covering whatsoever, and I am worried that it will be a really hot day and the cake will melt...or it will rain and the cake will melt...or it will be very humid and the cake will melt...

I understand there really isn't anything I can do to control or accurately predict the weather, but I guess I'm looking for help with being as prepared as possible. I know that just about everything in the cake world is negatively impacted by heat and humidity, but are some elements more likely to be affected than others? For instance, would I be better off covering with buttercream or ganache prior to the fondant? And how much of an impact would humidity have on the gumpaste flowers? Any tips or suggestions I can get would be greatly appreciated!

Yup, you have a huge problem. The only thing you can do is (on the wedding day just before delivery) go get a huge double walled rectangular cardboard box. Stand the box with tallest part up. Put non-skid pads on the bottom of the box then fully line it with frozen ice packs, the put a non skid pad on top of the ice packs and put the cold wedding cake on top of the non-skid pad. Close the box up and don't open it up again until you're ready to display it at the wedding. Put your cars air-conditioner on full blast,.................and pray.

What are they doing about the food they're serving? There must be some kind of shelter to manage that. What are their back up plans in the event of rain? If these are friends of yours I would question them about this issue. I've not done a cake that is being left outside but based on what I've read here on CC ganache is not a good bet for heat. There are some buttercreams that are more heat resistant (I think there's an IndyDebbie recipe on here that some like). I don't think the flowers will be an issue; not sure about the fondant though. I guess it is going to depend on how hot it is on the actual day and how long the cake is sitting out. The best bet is to have it put outside just before they cut and serve it. Again, finding out what they're doing with the food may be your best bet and have the cake stored there until serving time. Sorry I couldn't be of more help.

Ganache, no. Either IndyDebi bc or Charlotte's. Both are heat tolerant.

I agree, no ganache.

It will melt underneath under the fondant, and your cake will deform.

I would stick to a buttercream-covered cake, ultra smooth. Get it as cold as possible without freezing before delivering.

And yes, the bride and groom MUST have a weather back up plan! If they don't please do them a favour and tell them to do so! At the VERY least, too, your cake will need a shade like a gazebo or shade sail over it. And delivery it cold as you can. Make your GP peonies really early, and stage it so they are as dry as possible between layers. Place these on the cake at the site. Don't keep them refrigerated with the cake.

Use butter cream instead of ganache and try to use Hi ratio shortening since it's more stable and has a higher melting point. Fondarific states that it hold up to 100 degree weather so you might check out their product. I used Fondarific for an outdoor wedding several years ago but it was a May wedding here in Ca. Try to use gumpaste made with Tylose it holds up better in high humidity. Just made two batches tonight for a large cake I have to make a lot of flowers for in September. Indebys frosting is your best bet. You could always add several drops of white chocolate Lorann candy oil to your butter cream if you want a hint of white chocolate.