Climate and average weather in Turkey Because of Turkey's geographical conditions, one can not speak about a general overall climate. In Istanbul and around the sea of Marmara the climate is moderate. In winter 4 degrees Celsius and summer 27 degrees Celsius (39 and 80 degrees Fahrenheit) . In Western Turkey there is a mild Mediterranean climate with average temperatures of 9°C in winter and 29°C (48-84°F) in summer. On the southern coast the same climate can be found. The climate of the Anatolian Plateau is a steppe climate (there is a great temperature difference between day and night).