Hotter than it looks

Looking at predicted highs and lows for the heat wave that moved in, it doesn't look a lot hotter than it had been in the Atlanta area. But where it's really showing up is in how long it takes to cool off at night. When it cools off outside, I turn off the air conditioner and put a fan in a window blowing out, with another window open at the other end of the house. With the heat wave, it doesn't cool off enough to do so until 2am.