1. Pick the Right Weight:
It goes almost without saying that a Summer sport jacket should be light weight. Ideally you should chose a fabric that is light but not flimsy otherwise you'll effect the drape and structure of the jacket.
2. The Weave:
The weave of the fabric is extremely important because a tightly woven fabric restricts airflow, whereas an open weave fabric makes you feel every little breeze.
3. Opt for Texture
Unlike suits, which are often used in more formal environments, a sport coat is a bit more casual. It helps you to look well dressed without being overdressed, even if others don’t wear them. As such, you should opt for a fabric with some texture which will add to the casual nature of the coat.
Materials such as linen or cotton are often used for sport coat fabrics for that reason. Often blended with silk or wool, these fabrics are usually woven with yarns or irregular thickness, which results in little knobs and irregularities. These are by no means defects but intentional because they provide the fabric with that distinct summer look.
Even if you have the most openly woven fabric, you will still restrict the airflow if you add a lining to your coat. Linings are typically added to a suit to protect the outer fabric and to allow the jacket to glide more easily over the shirt that is worn underneath. We suggest trying out a half or quarter lining in your summer jackets. The lining remains in the most necessary places which helps protect the jacket, allow comfortable movement and keeps you cooler.
5. Go for a Pattern:
Some great pattern options include checks, seersuckers, windowpanes, and glen plaids are perfect.
Avoid stripes, including pinstripes because they look too much like suit jackets (it can end up looking like you're only wearing half a suit.)