Mid September . it's cheaper and the weather is great .

One of our writers, Evelyn Spence, recommends visiting Istanbul in the fall shoulder season (September/October) or in late spring. This way you'll avoid searing summer heat and crowds, as well as score better travel deals. Here's some more info on when to travel to Istanbul that she wrote for Away.com: http://away.com/destinations/best-time-to-visit-istanbul-wp-cid4174-sidwcmdev_158020.html