It's opened only when road/weather conditions warrant it. Safety is always first. Even if there is a lack of snow, there is usually leftover rockfall/slides, etc. from the previous winter that need to be cleared first. There is no set date to open the road that I am aware of. Each year is different.

CaT

If future generations are to remember us with gratitude rather than contempt, we must leave them more than the miracle of technology. We must leave them a glimpse of the world as it was in the beginning, not just after we got through with it.
- Lyndon Johnson, on signing the Wilderness Act into law (1964)