I am making 2 cookie bouquets for a outdoor party this weekend. It is going to be around 93 with HIGH humidity. the cookies are going o be covered in fondant with royal icing outline. should i be worried about the cookies melting? If so should i call the customer and let her know that they may melt and give her the option if she wants them before she pays so much money for them?

I don't know about fondant melting but royal has a hard time drying in high humidity. It will dry but it takes extra time. Here's a bump for you. Maybe someone else knows.

I don't deal w/high humidity but usually in high temps icings tend to dry out rather than melt. My feeling is it will be o.k.
You can't control the weather so customers should not be offended if something happens w/weather conditions.