You'd need to wear some clothes to sleep, but , yes, I think that'd be a safe lower limit. It's about what I did. I also wore a buff around my ears for just a little more warmth. They are easy to throw over you if you're sitting around camp, too. Note: I was in a tent, and my tent is good at blocking wind and is considered a "warm" tent. I was also on an inflatable pad rated R3.2 .