I remember sitting in the hot sun in a suit sweating your balls off getting dehydrated...
Or if you were in the UK, the opposite problem: getting frozen by the cold wind blowing round the upper levels of the football stadium you're in - or soaked by pouring rain, then having to sit in the stands (or in your car) slowly steaming in a soggy, creased suit!
(Note: of course, we did have hot days too during the conventions, but it depended how good the summer was each year - the rainy/cold ones were worse!)