Here is a web page of interest. It shows just how hot the 1930s were before air conditioning. This is for July. August was even hotter.
http://www.weather.com/outlook/health/fitness/wxclimatology/daily/USOK0537?climoMonth=7
Thee 1950s were also very hot!
I remember when I was a child during the mid to late 60’s and early 70’s the summer time temperatures climbing to over 110, in the shade, quite often. In the past 10+ years temperatures that high have not been common in the same area that I lived in back then. At that time all we had in our home was a swamp cooler - swamp being the operative word.