I've heard the like from northerners countless times, and I'm always amused by it. But, it's really the humidity that gets you, not the heat, as I'm sure you're well aware as a Houstonian. I vividly remember one August Saturday I was staying with friends that lived in Houston at the time. I walked out in the middle of the day, and their packed suburban street was completely abandoned, not a soul in sight, not a sound. It was downright spooky. I lived in the midwest when I was little, and the August Saturday streets in those higher, dryer, latitudes would have been full of people enjoying their summer.