When summer hits, it's easy to, well, take it easy. It's warm! It's bright! Time to shove that winter coat to the back of the closet, bust out a Hawaiian shirt, and kick back. And that's all well and good, if the activity on the docket is something like hanging out at the park or drinking a cocktail or two on an outdoor patio while the sun's still shining.

But sometimes you can't take it quite so easy. Sometimes you've got a meeting at work, or you're heading to an outdoor wedding where you need to look presentable in front of the groom's future in-laws. Nevertheless, you'll probably still want to feel like you're taking it easy—especially if the temperature is way up there and the idea of pulling on that suit you wore all winter fills you with dread.

That's exactly when you should be thinking about Alexander Skarsgård, and the relaxed-but-refined COS jacket he wore to the Dia Spring Benefit earlier this month.

SHOP $250.00, cosstores.com

It's seersucker, which ensures you won't be sweating bullets when you put it on, but it's not the traditional blue-and-white seersucker most of us are used to. Instead, it's done up in nice, dark navy that keeps it feeling that much more modern. The four-button front is a departure from a standard suit jacket, but that's what makes it interesting. It's a little fashion-forward—and, yes, a little more casual; probably don't wear it to any truly formal event—but rooted in a classic piece that every guy needs in his wardrobe.

Looking for advice on how to wear it? Take it from Skarsgård himself. A simple white tee, slim chinos, and black loafers are perfect complements to the jacket's dressy-but-not-too-dressy vibe. Or, if you're feeling bold, try it with that Hawaiian shirt—drinks on the patio optional, but encouraged.