First snow is generally mid-october to early november. Last snow is in mid-march to late-April. Snowiest months are January and February.
This is too broad a question to answer, since Colorado is large and topography plays a big part in its climate..In the mountains, it can snow any day of the year..I have waken up to 2" of snow on my tent in early August. The first snow is generally in Mid to late September in the mountains and areas near Denver to the north.. most of the state receives snow until May 1, but the mountains continue getting snow into early June..
If you check the records at the Colorado climate center, snowiest months vary according to section of the state..most mountain areas are very snowy Dec-March..
near Denver March and April are snowiest..while in sw Colorado, Dec, Jan, Feb are snowiest..some of the heaviest snowstorms in Denver and the foothills nearby can get 3-6ft snowstorms in March and April. I have experienced two of them that large so far...
IMPROVING THIS ANSWER
actually in the denver metro area it usually snows October... not September.
This year (2010) we are still awaiting out first snow.. it's sure to snow on Halloween though... always seems to. Last year (2009) our first snow was enough to close schools inluding colleges for two days in the Denver area. A few years ago it was lightly snowing into June. It really depends on the year, if its an El Nino year or not. 2009 was supposed to be one, and yes we did get a ton of snow. 2010 is supposed to be MUCH dryer. If your looking for skiing and such, know that many of the resorts make their own snow, and being at a higher altitude many of them are infact still getting snow.
Aspen, Colorado receives an average of around 150 inches of snowfall per year. Snowfall amounts can vary from year to year, but Aspen is known for its consistent winter snow conditions that attract skiers and snowboarders.
Colorado
The average annual snowfall in Bozeman, Montana is around 86 inches. Snowfall can vary year by year, but this is the average amount.
The annual average snowfall in Fairfax, Virginia is around 22 inches. Snowfall amounts can vary from year to year, but this is the typical average for the area.
The average annual snowfall for Cooperstown, NY is around 60 inches. Snowfall can vary each year, but this is a typical average for the area.
Aspen, Colorado receives an average of around 150 inches of snowfall per year. Snowfall amounts can vary from year to year, but Aspen is known for its consistent winter snow conditions that attract skiers and snowboarders.
Checking the Durango Tourism sites I found 68" to be the average annual snowfall for the town of Durango, Colorado. However, the Durango Mountain Ski Resort, just 25 miles north of the town of Durango, claims 266" of snowfall annually.
Colorado
DATA THROUGH 2002 YRS JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC ANN COLORADO SPRINGS, CO 54 5.2 4.8 9.3 6.7 1.5 T T T 1.0 3.4 5.4 5.1 42.4
3 foot of snow
Average snowfall is about 30" annually.
The average snowfall for Oswego NY is 140.3" per year.
The average annual snowfall in Bozeman, Montana is around 86 inches. Snowfall can vary year by year, but this is the average amount.
The annual average snowfall in Fairfax, Virginia is around 22 inches. Snowfall amounts can vary from year to year, but this is the typical average for the area.
The average snowfall in Muskegon, Michigan is around 89 inches per year. Snowfall amounts can vary each year, but this is the average over time.
The average annual snowfall for Cooperstown, NY is around 60 inches. Snowfall can vary each year, but this is a typical average for the area.
The average annual snowfall on Peaks Island, Maine is around 62 inches. Snowfall can vary from year to year, but this is the typical average.