Average daily high and low temperatures are often misinterpreted. They are in no way meant to show what temperature the weather is supposed to be. An average is nothing more than the average from the past, and the past is a very limited amount of time.
For example, now that summer is well past being half-over, daily average temperatures start to drop. However, this does not imply that the weather “is supposed to” get cooler now.
The record high today is 101 degrees from 1949, suggesting extremely hot weather is still quite possible this time of year. The averages drop in August because in some years, like this one, we get a little cooler before fall. Most years, the progression toward autumn is not steady at all. It turns cooler, then warmer, then cooler, then warmer. But gradually, the cooler trends become a larger factor until summer is just about forgotten.