I am making a wedding cake for my step brother at the end of May and it's outside at 6 P.M. Does anyone know if Sam's buttercream will hold up toTexas heat? I was wondering if I should just make an all high ratio recipe. ??

afraid i cant helpyou with sams, but indydebis does well in the heat, if you dont get an answer about sams.
xx

High ratio will hold up fine. You could even do 1/2 butter 1/2 high ratio

I've used Sam's and live in San Antonio. I wouldn't trust it to tolerate the Texas heat. Be on the safe side and go with a hi-ratio shortening based icing.

I'm doing cupcakes for a quince in June that will be outside and told the cusotmer their ONLY option with my icing is high-ratio shortening based. No SMBC or all butter b/c. Just can't trust it to stand up, but hi-ratio will do the trick.

Good luck!