Every morning when I check news and blogs on my computer, I always notice the daily temperature forecast for Seoul and my hometown. It always seems to me that Seoul is cooler. I looked online today to see if there was any archive data easily available, and to my surprise it is both available and easy. I was looking for high and low temps, but only found daily mean temperature. That is fine to prove my observation. Here is a chart I quickly made in Excel showing the temperatures for this year only (the data goes back to 1995, but that made the plot too busy).
I've shown it above in both temperature scales. Except for a few days recently, Seoul seems to be consistently cooler than Huntsville.