temperature monthly averages turkey
1 The mean annual temperature in Istanbul, Turkey is mild at 14.1 degrees Celsius (57.4 degrees Fahrenheit). 2  Average monthly temperatures have a variation of 18 C (32.4 F) which is a slightly low range.3  The range/ variation of diurnal mean temperatures is 7.8 C (14 F). The hottest month (August) is fairly hot with an average temperature of 23.5 degrees Celsius (74.3 degrees Fahrenheit). 2  January is the coolest month (cool) with an average temperature of 5.5 degrees Celsius (41.9 degrees Fahrenheit).