My high school physics class (of all places) taught me some amateur weather forecasting. I still use it to a degree. I stepped outside earlier (had to get another Diet Coke) and it was beautiful. Not too hot, nice breeze blowing. Now I need to see if I can explain it. I'm betting there's a high pressure system either directly over us or slightly to the west of us, causing a clockwise spin of air, bringing cooler air from the north down to us. Let's see if I'm right.
Well, I was kinda right. The high pressure system is over Ohio which is only a few states to the north and west of South Carolina.