Conditions are variable. Its hard to say how the snow will be from year to year. This last year the snow sucked but we were able to ride a little towards the end of Dec (as long as you aren't afraid to find some rocks every now and then). The Snowies are only 2.5 hrs away from Denver, Vail Pass is about 1hr 45 mins away but may be closed to snowmobiles depending on the depth of the snow, Cameron Pass is about 2 hrs away, Grand Lake is about 2 hrs away.