Soul

As a warm sleeper I would absolutely die in a 15 degree bag if it's 30+ out. I would have to fully unzip it and then struggle to regulate temperature all night. The Nemo gills help a little but they do not help enough if you're a warm sleeper and it's 15 degrees over your bag rating. I have a Nemo 35 degree bag that I use and I've never been cold in it even though the comfort rating is 40. If it's 50+ degrees out it gets too hot. 35-50 is definitely the sweet spot for it. Personally, as long as you're not in dangerously cold conditions, I'd always go with a warmer bag and wear extra layers to bed or have a backup quilt to throw over it in case it actually gets too cold. I've had way more camping nights ruined from having a bag that's too hot than one that's too cold. You can always add layers but once you have to fully unzip your bag because it's too hot you're in a tricky place with temperature regulation for the night. If you're a hot sleeper do not buy a 15 degree bag if you're basically only camping above 30 degrees. I would be looking at a 35 and then also buying a cheap synthetic camp blanket as an extra layer when needed or an only layer for nights that are 50+

This. I hate mummy bags. I move too much in my sleep. My Nemo takes up a bit more space in my pack but it is so comfortable and a good night’s sleep, where I can fully roll around in my bag, is worth it. I will never go back to a mummy bag.

It might depend on how you're built, but I can get my leg up like that inside my Nemo bag. I have short legs, though.

I really wanted to love the Nemo, but if OP is a smaller person, Id warn they have too much dead space.

Nemo. Best sleeping bag I have used. On my second one.

I'm a side/stomach sleeper and love my Nemo sleeping bag. I have a synthetic one and it's quite bulky, but the down ones would compress better.

Ok so it’s important to know that the degree rating on bags is the survival rating. This is the “you probably won’t die of hypothermia, but you’re not gonna have a good time” rating. Rule of thumb is to add 10-15 degrees F to any bag rating for the comfort rating. Always err on the side of caution with colder temps. If you get warm, you just open the bag. Some bags even have vents (my Nemo bags do). There are some tricks to stay warm with a bag, but for high 20’s, get at least a 15 degree rated bag. And have your son bring some good under layers to sleep in as a caution.