AI'm sure it's the humidity, but the swirls are sliding off my cupcakes. The swirls themselves are not melting, but sliding off in one piece. I thought about a toothpick between the layers of swirl but that only (potentially) works if I deliver them. Thought also about roughing up the top of the cupcake a bit where no one would see it, but not sure that would work. Suggestions? Thanks!

What icing did you use?   What containers are they in?

AButtercream. Once in bakery boxes the other time in clamshells

This can happen if you frost the cupcakes too soon after baking, if you frosting is too soft and the cakes are a recipe that gathers moisture on top after cooling, or if it is really hot and humid. The first two problems are easily fixed by waiting a bit or adjusting your recipe. The third problem can be solved by adjusting your butter cream recipe to one adjusted for high temperatures and humidity. HTH