I live in Chicago...mid 90's through the weekend with high humidity...no air conditioning...will do fine.
In times gone by, we had no air conditioning to cope with 90-degree temperatures, and we coped.
Sorry, pressed post too soon:
Wow so much either a lack of appreciation of the conditions in the past or lack of empathy. How much of each I don't know - you decide. How to respond depends on what you take as "times gone by" (Time isn't split into two parts, the now and a homogeneous past ), what is meant by "we" and what is meant by "coped"
1) Well no, on average, people wouldn't have had to cope with 90-degree temperatures so often. And on average the humidity wouldn't have been so high. Most importantly they wouldn't have had to suffer high temperatures for so long - which is the big killer - and they wouldn't have had to cope with such high temperatures at night which means there is little recovery period.
2) A lot depends on how far you go back. For this topic it is fair to take pre-industrialisation as one time period. Here people had more flexibility in work so if it was too hot they could move or do something else or do nothing. In southern Europe they still have siestas although they are less common and shorter than previously. Stupidly, Anglo-Saxons have migrated to warm environments e.g. southern USA but not picked up this culture. Also buildings/caves etc. were cooler: Remember warmer in cold usually means cooler in heat so best location for most extremes. Thick stone walls and small windows tends to be cool. We could design our buildings that way but it would most likely be a lot more expensive - are you willing to pay the price - both economically and aesthetically? Maybe we won't have a choice.
3) Post-industrialisation: Well, either you succumbed to the heat, in which case they literally stepped over your lifeless body and got somebody else keen for the work. I'd like to think we place a higher value on human life now. Or you grinned and bore it - but the stress placed on the body (along with all the other stresses) meant you were lucky to make it to 50.
Even in recent western history, in many ways it was easier to cope. A short commute walking or cycling to work. Large, cool offices - typewriters don't generate much heat. In the heat of the day, many streets would be deserted - everybody would either be at work, school or at home. Now the movement is constant, sitting in traffic jams delivering packages, take-aways etc. usually on a tight deadline and no chance for a break.
4) of course it depends who is meant by the "we". In the past, if you were the upper-middle or higher classes then of course you could stand the heat. It's easy if you don't have to do anything or there is a servant there constantly waving a fan or providing cool drinks. And in summer they generally moved to cooler climes e.g. the Raj in India going to the foothills of the Himalayas and Russian court going to St Petersburg. Commonly this is where we get our history from so of course, stress from heat isn't mentioned much.