|When you walk on snow when it is cold (-20° C), the snow squeaks; but when it is relatively warm (-5° C) the snow doesn't squeak. Why? — PW, Alberta, CA
Near ice's melting temperature, the surfaces within warm snow become more and more liquid-like. These liquid-like surfaces not only allow the warm snow to stick together as firm snowballs, but they act as lubricants so that the snow is particularly slippery. At much lower temperatures, the snow's surfaces are much more solid and they slide uneasily and noisily across one another. The cold snow squeaks because it hasn't "been oiled."