In the heat of a Wichita Falls sun in September of 1977....we were forced to do a big military parade. They had two ambulances standing by, and at least a dozen medical folks positioned around those of us in full-up dress uniform. If this had been done at 9AM....we might have been ok, but it was an afternoon event. There were three folks who collapsed, and at least another five or six who needed attention after the event finished up.
The problem is that when you stage some event in 90-plus degree temperature...you simply invite trouble. If it was a covered tent....you might get by, but it’s usually pretty stupid to have an event like this in such temperatures.
Yes, I’ve been in military parades too and have seen people around me keel over from the heat. They always told us to take in some salt beforehand, and to never lock your knees when standing there (I guess to help blood circulation).