A semi-casual combo of a polo and olive dress pants can be fitting in a great deal of settings. A nice pair of black flip flops is a simple way to bring a sense of stylish casualness to your ensemble. Seeing as it's roasting hot outside, this outfit is ideal and entirely summer-appropriate. Now that's how you dress casually at 30.
For relaxed sophistication with a masculine finish, rock a polo with olive dress pants. And if you wish to easily dial down this look with one piece, why not add brown leather sandals to the equation? A kick-ass ensemble like this one is just what you need on a roasting hot day. As you can see, after thirty you have a wide range of sartorial options.