There's going to be a huge difference between the base of a mountain and it's summit, like an easy 30-40 degrees difference. Not to mention the wind at the summit of the mountain is unhindered by objects in it's path and is pulled from the upper troposphere. It could have easily been -50F at the summit and -10 at the base.

 

For the MR crowd, same applies. I daily mine year-round in Minnesota, it sees below -20 and above 100, no problems to report. It does groan like an old man though if you don't give it some time to warm up in the winter months.