From: Northwestern Georgia, USA
High pressure usually brings clear skies, the coldest temperatures, and the least moisture. Low pressure usually brings moisture and comparatively warmer temperatures. Thus, clear skies and cold temperatures usually mean high pressure and low moisture are in place. When a low pressure system with moisture approaches it usually brings warmer temperatures, so when it's snowing the temperature is often relatively warm - 15 to 32 F.
The old saying "it's too cold to snow" reflects this although, strictly speaking, it's never too cold to snow. It's just that the coldest temps mean high pressure and that means little available moisture.
There are exceptions to the general rule. High pressure, cold temperatures, and high winds can produce lake effect snow - a situation that the residents of upper Indiana, Michigan, Ohio, Pennsylvania, and western New York know all too well.
< Message edited by Canoerebel -- 1/11/2010 3:06:00 PM >