A safe bet when looking for summer blazers, is to stick with light colors. That is an old fashion rule. Of course, rules can be broken, but there is a good reason behind this one: Light colors reflect a lot of light, and that is a great help in keeping you cooler. Light colors can also reflect a more casual attitude and way of dress than a darker color would. Plus, colors like white, tan, and light blue look great with formal outfits, and with casual jeans and T-shirts as well. Pick something versatile, that you will get plenty of use from.
Here are three examples I find very nice:
Summer blazers for men pictured:
Left: Jones New York Men’s Two-Button Blazer, Blue Chambray
Middle: GUESS Brant Floral-Print Blazer, sage
Right: Jones New York Men’s Two-Button Linen Blazer, tan
If you are getting a jacket for a formal occasion, you could go for something double-breasted. Be aware that whatever light color jacket you get, it is likely to get dirty much quicker than a darker jacket would. You are bound to have to wash it fairly often, and so it is very important that you follow the manufacturer’s washing instructions if you want your blazer to last a long time. Most of these jackets are probably dry-clean only, and you should take that into account before buying one. Dry-cleaning is not cheap.