And it's only in June, July, and August that the nighttime average temperature is in the 80s. September and October's are in the 70s, and then you're down to the 50s (or even lower!) for the next five months before it starts warming up again in April and May. So even though the high temperature is much too hot for six months out of the year, you only get three months of lows in the 80s (and they feel relatively good). It may be too dusty here to keep the windows open much when it's cooler, but we can at least open them in the mornings for a bit when it's nice outside.
I'm putting this on the win column of my mental chart of reasons to like living in Riyadh (or, at least, why Riyadh isn't as bad as you think it is).