To keep feet cooler while running in hot weather many people like to run in the thinnest sock possible. Thin socks unfortunately provide little protection from hot spots and blisters. Running in hot weather feet quickly get hot and perspire, causing socks to become wet. Moisture significantly increases friction (stickiness) between socks and skin. The higher the friction, the hotter the feet and the greater the chance of getting blisters. Higher friction limits skin surface movement, but still allows inner tissue movement. This shearing effect physically separates the two layers which fill with fluid forming a blister.