As the temperature rises, so must your hemline. Off the Wall One of our favorite lines, Wren, makes a splash with a cotton shirtdress ($315) that’s truly a work of watercolor art. Overall Winner When the heat wave hits, keep cool in cotton and look new wave chic in a cut-to-breathe overall dress ($122.50) by A.P.C.Petal Pusher This floral knee-length number ($295) from Built by Wendy will keep you covered, literally, as you bike around town.Gal Friday Hit the office in Madewell’s boardwalk-strolling getup ($145) to remind your boss it’s a summer Friday, and you have plans.Frill Seeker The flirty ruffles — and useful pockets — on the sweet Geren Ford flora silk dress ($226) add up to one laid-back but ladylike look we love. Not your style? Don’t sweat it. Choose from more than 80 cool summer dresses.