Weather in Mammoth is tricky for a few reasons. First off, it’s in the mountains and more than once I’ve seen snow materialize from a 0% forecast and a foot of snow vanish on the forecast vanish to a clear sky.
Also, there’s the altitude. Down near the 203 and 395 intersection, the altitude is around 7,000. Where I live (Old Mammoth) is 8,000. Main lodge is 9,000, McCoy station (gondola mid-point) is 10,000 and the summit is 11,000.
So between the 395 turnoff and the top of the mountain is 4,000′ feet of difference in elevation (4/5 of a mile). An inch of rain in town can easily be a foot of snow at my house and four feet at the summit.
If you move to or are staying in Old Mammoth, find a good snow shovel. Learn to love it.