This past summer in late July, I wanted to take my new ride out for a test run.
The temp in Reedley was over 100 degrees so I headed to my local BMW Dealer in Fresno and Al hooked me up with a "Hydroweave" vest, sold by Silver Eagle outfitters (www.CoolingApparel.com). You soak this vest in cold water for 5 min. and then put it on.
I gave this vest a real workout as I rode almost 200 miles in 100+ temps and the thing was still damp when I reached my destination in Pismo. It really did keep me cooler.