I was at Okemo yesterday. 9 degrees at the base and 0 at the summit. And thats not even counting wind chill. 2 out of the 5 times I rode to the summit I took a quick stop at the summit lodge for some water and some hot chocolate. Got nice and warm and then continued to ride. Even with my brief warm-up breaks I managed to get in 12 runs total on the day.
The Jackson Gore side actually felt warmer than the south face. Wasn't much wind over there and far less crowded. Also found the manmade snow to not be that bad. Very few bulletproof patches which really surprised considering the temps and lack of snowfall