When I interviewed for a job two months ago, I was a hot mess. But nerves weren’t to blame for my sweaty brow—my suit was. You see, it was 88 degrees in New York, and the natty navy number that had seemed just the thing when I packed it back in London had turned into a wetsuit as I raced from Brooklyn to Midtown via the inferno-like subway. Instead of breezing into the meeting with the nonchalance of Serge Gainsbourg, I galumphed in like a hot, steamy lump of worsted wool. My now-boss turned a blind eye to my alarmingly crimson complexion, but I’ve since wondered what two-piece would have best kept its cool in such sizzling conditions. So began my hunt for the sweat-free summer suit.

Such a search is no longer confined to classic materials like linen, puckered seersucker or fresco, a well-ventilated wool with an open weave. Mills are creating “sexy” mohair-wool blends that let the air in yet retain a rakish luster, said New York tailor Paolo Martorano. And there are carefully engineered warm-weather hybrids merging cotton (light but not always breathable), linen (breathable but easily creased) and silk (wrinkle-resistant), as well as newer eco-friendly fibers like hemp and bamboo, said Mr Porter’s style director Olie Arnold. You can also take your pick of sporty synthetic styles—Veilance makes a popular machine-washable nylon-elastane set—but if you’re after a suit that doubles as an air conditioner, “I would always trust natural fabrics,” said Mr. Arnold.