I disagree that it's nothing like we get here. I was walking for exercise (about 5 miles a day) just before our first August trip and I had worse days doing that here during a heat wave than I did on any of our August vacations. It's about the same, but at least I can pop into air-conditioning every 5 minutes if I want, or take a pool break on our vacations. The 5 mile power walks? I just had to keep walking.
We never find it too bad. Correction, we do find it bad, and when we do, we promptly adjust the plan and do something to cool off. Miserable would be forcing yourself to keep plodding through it without taking a break. We never ever do that.