Flagstaff is at 7,000 ft elevation. According to usclimatedata.com, average hi/lo for November is 52/18. Average snowfall is 7". As a former resident, I've seen snow on the peaks as early as October. Other years barely any at all. You will most certainly want to be prepared for extreme cold weather.
Steward, Arizona Trail Passage 23c (Mazatzal Divide Tr, Barnhardt to Red Hills)
...he's got the Mazzic hands...