@Nia:
Ah, also sorry I spelled your name wrong. ^^;
No problem. K…C... it sounds the same.
@Muda:
Whoa, where in AZ!?
I'm in the Phoenix area, too.
As long as you have AC, you'll probably be fine. Granted, I don't have too many figures, but I've only ever had the problem I mentioned before (which I could have avoided easily) and a cheap gashapon figure that leaned. At least that I've noticed so far.
Some issues like leaning are caused by poor design, not just heat & humidity.