Gingerbread houses caving in due to weather

How can I explain if December is unusually high temperatures this year why someone's gingerbread house might crumble or cave in to a customer?

My family owns a bakery and last year the weather was way hotter and more humid than any other previous years and the houses didn't stay together and some actually caved in after getting soft. This has never happened in previous years and I am trying to come up with a way to explain what is happening to our loyal customers so they know it's not someone we did in the baking and it's the weather which is out of our hands?