Leif Treader:
You realize that whatever forecast you get becomes inaccurate as soon as you start traveling? Altitude alone is the difference between snow and rain, and distance can turn it all into sunshine.
That's possible, maybe even likely, but sometimes the weather patterns are the same (or very similar) for a large area, like say the mountains in Northern CA between Truckee, CA and Reno, NV, for example.
Besides, people on foot don't quite have the mile (or km) eating pace that vehicles do.
Also, why not attempt to get a daily weather report, if one has the resources to do so?
Oh, and finally, doing so is a part of Dakarian's daily rituals. Morning prayers and the like. :)