I do a much, much shorter route located further north and two mountain passes in a row (and once you're committed...). I usually check the weather forecast for a couple of towns in the area + the origin/destination in the area (at a lower elevation than the passes) - these bracket the mountain ranges - and then account for likely temperature at the passes. This gives me an idea of whether there will be inclement road conditions or not. If you're familiar with the terrain on the route, you could do the same though it'd be a lot more research for you.