average temperature for hanoi
1 The average annual temperature in Hanoi, Vietnam is fairly hot at 24.1 degrees Celsius (75.4 degrees Fahrenheit).2  There is a variation of mean monthly temperatures of 13 C (23.4 F) which is a low range. 3  The mean diurnal temperature variation/ range is 7.1 C (12.8 F). The hottest month (June) is very hot having a mean temperature of 30 degrees Celsius (86 degrees Fahrenheit). 2  January is the coldest month (very mild) having an average temperature of 17 degrees Celsius (62.6 degrees Fahrenheit).