Here's an easy chart to read to see where the human body is most comfortable ;)
https://hsiehy3.files.wordpress.com/.../psy_chart.png
I hate the psychometric chart but it contains a lot of information. Once the dew point is above 70 it's downright oppressive. Nowhere for the sweat to evaporate because the air is already saturated. You need a consistent breeze or a fan to stay somewhat comfortable. Dewpoint is already 68 this morning. Calling for a high of 95 and the humidity is currently at 94%. Can't wait to work on a roof all day :)