I spent my younger days living in Las Vegas and adapted fairly quickly to the heat after moving there. However there was always three qualitative steps when it came to heat, when temperatures cross 100F (38C), when they cross 110F (43C), and when they cross 120F (49C).

Generally the temperatures stayed below 110 but it was pretty easy to know that the temperature was "over 100" or "under 100". Once the temperature got to 110 it started to feel oppressive. Out by Lake Mead where we would sail and play on the 'beaches'[1] when it occasionally crossed 120 it actually started feeling threatening. Even in the water I always felt "You must get out of this heat" when it was over 120. Sort of an existential threat to health and safety.

The interesting bit is the water carrying capacity of air when it is warmer. As global temperatures rise, the amount of water vapor in the atmosphere goes up. If that turns into clouds in the stratosphere it continues to get hotter, if it turns into clouds in the troposphere it gets colder.

[1] We called them beaches but really its just the desert running into the water that is backed up behind Hoover dam.