It's the tail end of the hot season here, which means the daytime highs are in the very upper 90s and so is the humidity. When the sun is out, it's blistering. In the shade, with any breeze, it's not quite so bad.
The first day was totally miserable but I've kind of started to adjust. That doesn't mean I sweat any less, just that I don't feel quite so miserable while doing it.
With all the sweating, drinking water is a necessity. The hotel provides 2 bottles of water each day with housekeeping but that's just not enough. Having been warned against drinking the tap water, I'm buying LOTS of bottled water. On the one hand, I'm glad it's relatively cheap. I can get a big (1.5 liter) bottle for 15 baht (about 45 cents). On the other hand, I feel really bad about all the plastic bottles I'm tossing.