What defines a 3 season bag temp range wise?

Honestly I am sure you will get lots of answers because there are so many variables.

Sleeping comfort depends on lots of things … hydration, layers, calorie intake, etc.

3-season also depend on your locale … 3 seasons in FL, not the same as 3 season in MN.

RE: ratings … again, you’ll have to find based on your experience what those numbers mean to you … some might be comfortable lower than a bags ratings, others might not even get to that rating before being uncomfortable.

Bottom line … varies based on individual.

Well Im still going back and forth on sleeping bags. Like I mentioned in another thread I got the Sierra Designs Zissou 3S which weighs 2lbs, 15 oz and can keep me warm in the 20s. Ive tried it at home and its very toasty, I can tell, and its super wide and comfy for a side sleeper like me, opens on both sides (partial one side).

So now, Im trying to fig out what lighter and less warm bag to get for not so cold temps. I ordered and received and tried at home a Marmot Hydrogen. It feels a little claustro for me width wise, not sure I will keep it…..? Other than that the weight and temp specs are I think a good choice for spring and well sleeping on top in summer. But again not wide enough….

So for my 2nd not so warm bag, for late spring/summer….I am finding a variety of wide cute bags by Nemo, Sierra Designs, Sea To Summit rated EN Comfort anywhere from 30-36 and weighing 2 lbs 2 oz to 2 lbs 6 oz…..which is not that much lighter than the 3S I mentioned above at 2lbs 15 oz…..make sense? And not sure if 36 EN vs 30 is a good idea.

Thoughts? :)