Yes, I found that out this weekend. 22*F on Friday night with a dusting of snow, 13*F last night with 4" snow by the time we woke up. Brought an REI 3.5" for me, Ridgerest for the pooch, and my Neoair as a backup, which is good because one guy in the group didn't have a decent pad.

I use the Neoair on by GHB. It is small enough to fit in one of the outside water bottle pockets, but I carry it inside the bag to help prevent damage. For an air mattress it does a good job of insulating.