When it comes to lightweight tops, you can never go wrong with a good henley. Taylor Stitch and Mission Workshop have taken the staple and upgraded it with 12.5oz Merino Wool, which is temperature regulating and odor resistant. They've also given it a hidden back pocket, a button hole to run your headphone cable through, and Unbreakable Japanese urea buttons along the shirt placket. The shirts are available now for pre-order ($88) and ships in late July. 

$88, taylorstitch.com