Dont know where you got this, but I intend to try it out. I live in Texas and sometimes I think some of the horse folks around here are crazy to ride horses HARD in the supreme HEAT. If I am totally uncomfortable and reaking wet from sweat, I figure my horse must be feeling it worse than me!! Thanks.
Here in NC, we have to hot, humid summers. I rarely ride during the heat of the day when it's over 90 degrees because of the humidity, or the mares will literally be dripping sweat from their chin to their butt. It doesn't seem to bother them at all, but it's much more comfortable for me riding very early or late in the day anyway.