When the temperature surges past seventy or so, it's time to shelve your wool suits and go lightweight. Yes, khaki is probably the best-known of the summer suits, but don't limit yourself: Designers are doing a range of cotton options, including navy, black, and even plaid. Whether you have the cojones to pull off a white one is your call. Other go-to cotton options include seersucker (go with gray or pale blue stripes) and whipcord or LINEN. Linen is good.