Green Geometric Print Jacket

What would you wear for a formal event at this time of the year? I prefer something loose and boxy. Colorful, but not over-the-top. I love this coat/jacket by Milly. Its a beautiful and extremely comfortable coat which I wore out on a warm day and didn't sweat at all. I, of course did take it off to reveal this beautiful white Erin Erin Fetherston dress, paired with my white block sandals.
Outfit Details : Shoes - ASOS (unavailable but like this) | Dress - Erin Erin Fetherston | Coat - Milly