With the onset of this heat wave in NYC, I am recalling the great Chicago Heat Wave of 1995. For five days the temps were 100 or more degrees But added to that was extremely high humidity so the heat index reached 119 °F (48 °C) at O'Hare airport, and 125 °F (52 °C) at Midway Airport. Over 700 people died due to heat stroke. I was working as a dogwalker that summer, driving around in my old car that had no AC. The worst day the temps got to 106. After being outside in the sun and already feeling extreme heat exhaustion, I had to make a phone call on a payphone in an large parking lot near my apartment. It was 5pm and there was no shade. For some reason the phone company had shut off my phone and I had to wait for over an hour to get through to an operator. I should have left and gone inside when I started to feel the heat stroke coming on, but a person becomes delirioius and irrational in that state, so I just stayed. Eventually I stumbled home (which had no AC) and managed to make it down to the basement where I passed out. My roommate was freaking out and when I came too I told him to put me in the shower with cold water running. I stayed in the shower for a long time, there was so little water pressure because every hydrant was opened by the kids in the neighbhorhood looking for some relief. I remember finally feeling my body temp going down and my mind becoming a bit clearer, but I was in a bad state the rest of the night. It's like when you have an extreme fever, you pass into a state of delirium and hallucinations, that almost feels pleasant. I guess at some point the body can only take so much before it says to the brain to shut down. I think that is how so many died. The elderly in a weakened condition already started acting irrationally in the heat and probably not doing some simple things to help keep them cool. In several instances some people who were found dead had working AC in their apt. but had never turned them on. Here is a description of heat stroke and heat exhaustion... one common mistake people make is that if you drink plenty of fluids you should be fine even in extreme temps. But  if you are in the sun and there is high humidity our bodies ability to dissipate heat shuts down and body temps rise despite being hydrated.

Heat exhaustion: Heat exhaustion is a warning that the body is getting too hot. Those most prone to heat exhaustion include elderly people, people with high blood pressure, and people working or exercising in a hot environment. A person with heat exhaustion may be thirsty, giddy, weak, uncoordinated, nauseous, and sweating profusely. As with heat syncope and heat cramps, the body temperature is usually normal in heat exhaustion. The heart rate (pulse rate) is normal or elevated. The skin is usually cold and clammy.

Heat stroke: Heat stroke is a serious, life-threatening condition that occurs when the body loses its ability to control its temperature. Victims of heat stroke almost always die, so immediate medical attention is essential when problems first begin. In heat stroke, a person develops a fever that rapidly rises to dangerous levels within minutes. A person with heat stroke usually has a body temperature above 104 F (40 C), but the temperature may rise even higher. Other symptoms and signs of heat stroke may include confusion, combativeness, bizarre behavior, feeling faint, staggering, strong rapid pulse, dry flushed skin, and lack of sweating. Delirium or coma can also result from heat stroke.

I have heard of several people committing suicide by heat stroke... will attempt to find out more.