Hi there !! I'm novice,  self-taught Baker I do have few recipes down from scratch Italian meringue buttercream, cake's  recipes Etc. 

Recommendations

what is the best icing for a August wedding cake event ???

Thanks 

when you say august -- you mean in the states when it's hot or in what country and is the reception indoors or outdoors

Not knowing the answers to the ?s K8 asked here is a great b'cream that I have used in temps from 40s degrees F to over 100 degrees F.  I'm sure it will work well for you:  https://www.cakecentral.com/recipe/22469/2-icing