There are lots of options to keep cool(er) by exploiting simple evaporation. I tend to run hot, and have in summer months often resorted to sleeping with a damp towel on top of me and a fan whirling above. Cooling cloths jammed under helmets are typical construction-site headgear here in the southwest, too. The problem with most cloth—like plain cotton— is that while it stays damp too long when it’s cold (so it’s a bad choice for winter clothing) it does the job of evaporation all too quickly when it’s hot, and requires frequent re-wetting. (Not to mention, can get other surfaces sloppy and wet when newly soaked.)
High-tech fabrics can make up for that fault, though. I grabbed one of these cooling towels from Frogg Toggs as an impulse buy at Bed, Bath & Beyond a few weeks ago; I was only in the store to make a return, but that was one more in string of days over 100F, so I was easily lured in by the promise of some temperature relief. In the time since, I have been wildly happy with it, and have taken to wearing it in my office (second story in a hot climate; heat rises), which helps me put up with miserly use of the A/C. On the 4th of July this year, I walked around San Antonio with it on my neck, which augmented my sunscreen as well as made me noticably more comfortable. (My friends also borrowed it to help soothe their one-year-old baby while we watch the fireworks that evening.)
I haven’t tried using it in truly awful humidity yet, but Austin’s heat has been coupled with some moisture lately, and this towel defintely never stopped being an effective cooler; the drier the day, though, the better. (In a moist enough climate, it might end up feeling more clingy than cool.)
There are special cloths with phase-changing crystals embedded that similarly hold water for more gradual evaporation compared to a plain cloth; I haven’t tried them and can’t compare. But I like that this one is simple and requires no special care (machine wash, store damp). Here’s a competitor called Chill-Its that appears similar and may be just as good.
I count three small shortcomings, none of which dissuade me from strongly recommending it. To me, the pool-equipment blue of the one I bought is considerably less obtrusive than fancy-patterned bandanas or more garish safety-oriented colors, but I’d much rather have bought one in black or white, for something like subtlety. (It does come in grey, at least.) Second, I wish there was a larger size; it appears to come in only one size. On the hottest Texas days, believe me, I’d tolerate even the ugliest pattern to wear something like this equipped with a hood and full shoulder coverage. Even 20 percent bigger would make it much better, esp. as a replacement for that wet towel for sleeping. Finally, though the packaging promises “hours” of cooling, I found that it certainly didn’t stay wet even any longer than two hours. That’s mildly annoying, but easy to fix with another water application; it still beats a wet towel severalfold