| Often seen in weather reports, the snow level is the lowest elevation at which snow is falling (generally it has to be accumulating too, mushy slushy rain doesn't count). This is most often seen in areas with relatively warm climates but high mountains, like California. (In places like Montana, the snow level is irrelevant, because it's so cold snow is falling everywhere; it would snow far below sea level). The snow level can be important to know for several reasons. For instance, if you are trying to get over the Grapevine, you know that if the snow level is at 4000 feet or below the road will be nasty and icy. If you want to go snowboarding at Sugar Bowl, you would hope for snow levels below 6000 feet, because snowboarding in the rain just sucks. This weekend I'll be camping in the low hills near Lake Berryessa at around 1500 feet. A freak storm is expected with 'possible accumulations of up to 10 inches of snow above 1000 feet)... it will be interesting, and a cold rain to say the least.
Generally, the snow level seen on the weather reports is not exact. True, the transition where rain turns to snow is usually very sudden, but it is hard to pinpoint exactly where it is. I've noticed that the snow level is sometimes associated with the level of the clouds backing against the mountains, but this is hardly a reliable rule. Also, things may get complicated if there is cold air at the surface. The snow level can be relatively high, but rain can re-freeze when it nears the surface, causing sleet, or an ice storm. | 
