I like light blue in Summer. I think it's lovely to look at. All too often Summer opens itself up to losing the clothing and skimp-afying everything. I say why, why can't we refine the Summer heat into elegance. It's the attitude anyways .
In my opinion, I think wearing black to a formal event in the Summer is harsh. It doesn't blend to the environment and brings a strong shadow feeling to the strong light. Lighter colours feel like a surrender, in the harsh Aussie climate anyways.
So wear your coolness and your relaxation.