Necessary quilt temperature rating for the JMT
Will I be warm enough on the JMT with a 30F quilt, supplemented with clothing as needed? Here's what I have:
30 F quilt (apparently comfort rated to 42F)
alpha 60 leggings, hoody, and socks
wind pants, wind jacket, sun hoody
down puffy with ~1" of loft (SDUL 1.1)
light fleece beanie (layered with hoods from alpha hoody and wind jacket)
Context:
sleeping pad will be a Switchback, R value 2, perhaps supplemented with a thinlight for total R 2.5
first 2 weeks of August, NOBO
I know, I know, nobody can answer this question for me. As soon as it warms up some more, I'll get out for some shakedowns and find the answer for myself. But in the meantime, I'm trying to talk myself in or out of investing time into 20F quilt hunting.
I've researched this question several times. Some people claim 30F is totally fine, some people claim it's not even close to enough.
The HalfwayAnywhere 2023 JMT gear survey claims that the average temperature rating among quilts and bags is 17.6 F. The average temperature rating of hikers that wished they had something warmer was 19.7 F.
Those stats seem damning, but honestly, there is not enough information here to make any real conclusions. How many of those hikers were not sleeping in fleece and extra layers of down? We don't know.
Notably, the average pack size among JMT hikers was near 55L, and average baseweight near 20 lbs. Suffice it to say that the survey respondents largely are not UL hikers. Thus, most people were probably not explicitly including clothing in their sleep system.
So I'm looking for true UL insights on this question. I do not want to carry more insulation than I need. And I also don't want to pay $300-$500 for a 20F quilt, when I own a high quality 30F option, and already shelled out on a puffy.
I also own an alpha 60 bag liner that I could add on for insurance, but it adds more weight than I want to consider. My current 30F quilt is ~16 oz, and the alpha liner is ~6 oz. I do not want my quilt to exceed 20 oz.