Here are some of Turkey's main festivals which take place annually.  

Please check the www or with their Tourist Boards to find exact dates closer to the time you arrive.

Turkish festivals and yearly events.
A complete list of festivals

 International Film Festival, Istanbul, April
 International Children’s Day, Ankara, April

International Marmaris Yacht Festival, Marmaris, May
 International Tea Festival, Rize, June

International İstanbul Festival, İstanbul, July
 Kırkpınar Oil Wrestling Festival, Edirne, June/July

International Aspendos Opera and Ballet Festival, Antalya, June/July
 Mengen Chefs’ Festival, Bolu, September

Mevlana Commemoration Ceremony, Konya, Mid-December
 Istanbul Polonezkoy Cherry Festival, Istanbul, June


Rock'n Coke, Hezarfen Airfield in Istanbul, September
Turkish rock festival sponsored by Coca-Cola. It is traditionally held at the Hezarfen Airfield in Istanbul, Turkey.