A perfectly tailored suit is appropriate year-round—it's the suit fabric that's seasonal. While heavy wools and tweed jackets look fantastic during work or holiday in the winter climate, they're nothing short of suffocating in the warmer months. As we have summer all year long, opt for lightweight layers that you can wear inside and out, during the day and at night. The key to not sweating is all in the fabric. Here's what to look for.