It's even more interesting that many Julys prior to 1979 were warmer still. Our (humanity's) temperature records aren't very good before 1895, but the long-term (many thousands of years) temperature record shows that much higher temperatures existed within the time frame of human existence:

https://en.wikipedia.org/wiki/File:Holocene_Temperature_Vari...

http://www.longrangeweather.com/global_temperatures.htm

Going back even further, the record shows that it was MUCH hotter before then:

https://en.wikipedia.org/wiki/File:Five_Myr_Climate_Change.p...