Ant.....
As for being ignorant of flying well, not totally. I know the basics, like what "hot and humid" conditions means in terms of lift. I also know that Denver airport is at something like 3000 ft and that adds up.
KDEN is actually 5431ft amsl (above mean sea level).
In July the temperature will frequently top out at 30deg C or 86F, giving a denisty altitude of over 8000ft.
The degradation on aircraft performance is very marked in those conditions - but then I suspect you don't really want to know that anyway!
BTW it is hot and high that matters more than hot and humid.
As to the ATR specifics, I can't comment, but what I CAN say is that these conditions affect all aircraft to a degree.
KPHX at 42degC in a 747-400 even at 1300ft amsl, equates to a density altitude of about 6000ft - a considerable consideration for an intercontinental flight to Europe. Start talking then about Bogota at 8400ft and 18deg C, or Mexico at 7500ft amsl and 23deg C and you are really talking about aircraft envelopes!
In the meantime, do your research and you may discover the truth!