No - I used to live and run in Indiana. I ran 1/2 marathons all the time and I never carried water or wore sunglasses. I don't know if its because I was young and stupid and lucky or because the humidity there is so much higher but I never had any problems. I did drink at the water stations when I ran races but my rationalization for that was: I was running faster since it was a race. My question to your friend would be - did she show signs of dehydration either during the run or after? If not - she actually could be OK.
Life should NOT be a journey to the grave with the intention of arriving safely in an attractive and well preserved body, but rather to skid in sideways, champagne in one hand, strawberries in the other, body thoroughly used up, totally worn out and screaming: "Yeah Baby! What a Ride!"