The summer sport jacket!

Gant at Barney's

Sport jacket is usually defined as NOT being a suit jacket, meaning not having a matching pair of pants. That same fact allows the sport jacket to be more bold in fabrics, colors and patterns.....
Going back in history into the roots of the sport jacket will take us to the mid-nineteenth century where men started to look into more comfort and less formality in their jackets, Over time out of the sport jacket we got the blazer....what's the difference?  well its most historically.... the sport jacket has its roots in sports and more specifically as the hunting jacket known mostly in tweeds with elbow patches and flap pockets, while the blazer has a nautical roots with a club's patch on the left chest pocket, patch pockets and metal buttons.
So since we are talking summer let's make room for bright colors, bold patterns and fun textures....wear you sport jacket with jeans Chino or even shorts, pair it with T for a casual feel or dress it up with a shirt, a tie and  for fun add a colored pocket square.... 
As always i recommend a well fitted jacket, make sure that the shoulders fit you well and are not too big cause that will make it look frumpy and cheap, nice fitted shoulders like in the red jacket below from Devon Scott will make you look like a million dollar whether you wear it with a T or a Tux shirt...

 Below fitted red jacket from Devon Scott and striped from Polo

 Below bold pattern in Comme Des Garcons and Green jacket from Jil Sander

 Below denim jacket from Paul Smith and bright blue from Jil Sander

 Below 2 jackets from Neil Barret

 

Below  Asos and Arsenal