Sierra late September sleep system.

I’d bring the 22 and leave the half-pound liner at home. I might bring the hood but I wouldn’t bring the socks because my feet never get cold.

I can’t answer which system you should bring, but I will say that it is quite possible you will find temps down to 15 degrees F or even lower in late September…and that can include up to a foot of snow.

Will you get those conditions on your trip?  Ask me a week before you leave, and I’ll give you an answer!

+ 1 to what Paul said. I got snowed on once in the John Muir wilderness in the middle of Sept.  If you are travelling by car, I would bring both sleep systems and make the decision based on the last weather forecast you can get while connected to the internet.

I personally would probably bring a down sweater or light fleece no matter what.  Sounds like an awesome trip.

Given that we are in extreme drought in California and high fire danger, there  might be be an open flame/stove ban in the Wilderness Areas managed by the Inyo National Forest in August. So you might start planning meals accordingly.  Of course in case of emergency, for example it starts snowing and you cannot move by foot, it is allowable to start an emergency fire so bring sources of ignition.

Hit 15F plus 30mph winds/snow in late September of 2019. Had 30F comfort rated quilt and it took everything but the kitchen sink to keep warm that night.

Hopefully, the smoke season will be over by then.

Ditto, Bring the warmest stuff and don’t forget your quilt rating is at least 10 degrees higher than sold.