what happened to the heat?

Last week it finally felt like summer.  We ran the AC all day Wednesday through Sunday evening.  And then last night the coolness rolled in and it stuck around.  The air today wasn't warm, what the heck?!  I want more than a week of summer.  On the plus side, the cooler temps gave me a break from the constant watering I need to do to keep all the plants from wilting in the heat.