I am making cupcakes in June in Texas (hot) they will be outside for a time. What covering works the best do you think- buttercream, fondant, poured fondant, or rolled buttercream? TIA

Whipped cream Buttercream in the recipe section. It's heat stable. Really.
PS - there's no whipped cream in it. It just comes out the consistency of whipped cream.

I use Indydebi's recipe. It holds up well for me, and I'm in Arkansas.

Sugarshack's recipe. Tried and true in the heat and humidity. LOVE it.

Make a batch of all 3 suggestions, and then pick for yourself!

I use Indydebi's recipe and it holds up to extreme heat and humidity. As long as your buttercream recipe is all shortening you shouldn't have a problem. Butter has a lower melting point than shortening so I never use it in the spring/summer months.