PCT Thru Hike Sleeping Bag

The 20°F is enough unless you're starting before mid March. If you do find you're cold, you can temporarily add an inexpensive down vest. I'd assume you already have insulation for your torso, so the vest can be placed over your legs. A heavy Cabela's XL down vest is 13 ounces, and cheap enough compared to a WM bag that you can leave it in a hiker box when you don't need it any more.

@Austin,

I did a poll on the pct-l last year asking about sleeping bags.

Those who were not using the Marmot Helium (which made up the vast majority of the votes) were using the WM UltraLite.

I should note that over 80% of those who participated also stated that they also used a silk liner.

–Abela

I used a WM Summerlite (rated to 32 degrees) on my thru and would do so again. I had a bivy sack and silk liner which added a bit of warmth, and I slept in my Thermawrap a lot of nights. But I can only recall 4-5 nights where I was cold, and even then it was not a major problem. YMMV.

I used a WM Alpinlite from Mexico to Tahoe, swapped out for a cheap Kelty synthetic 40 bag Tahoe to Ashland, OR, and used the Alpinlite from Ashland to the Canada border. There were some cold nights early, and unexpected rain in OR and expected rain in WA.

I was happy to have the 20 degree bag when I did. Just slept in thin long johns and dedicated sleeping socks.

It was nice having a synthetic 40 bag that I could get dusty, grimy, sunscreeny, mosquito-repellenty during the hot days north of Tahoe. The Alpinlite is too warm and too nice to do that to!

Never mind. I used the search bar and found my answer :)

I think the Ultralite's temperature rating would be sufficient during this trip, but the Versalite weighs only three ounces more, and it's ten degrees warmer. That's what I'm conflicted about. I'll likely have this bag for many years, and I plan on using it during many trips. During this bag's life, it will likely lose a lot of loft and warmth due to compression and use. That's why I'm leaning towards the Versalite. I'd like to use whatever bag I choose on another long distance hike after this thru-hike, even with this bag's loss of loft and warmth. Since the Versalite is warmer, I think it may be better capable of losing loft and still being suitable for another thru-hike after this one. Any thoughts?

I think you will find either warm enough for a PCT thruhike (I successfully used a Megalite the whole way in 2007).

The main difference between the Ultralite and Versalite (beyond the warmth) is the girth. A lot of bigger people do not fit comfortably in an Ultralite (59" shoulder vs 62" in a Versalite vs 64" in a Megalite). If 59" girth is comfortable for you, an Ultralite is a bag that you will never regret buying.

I wouldn't worry about the 3 oz, and I personally would go for the 10 degrees warmer. It's easy to unzip the bag, or lay it on top of you, but it's nice to have that little bit more warmth when you need it. My bag approach is a 20 Alpinlite and a 35 Caribou MF; covers about everything I need.

And depending on how big your frame is, definitely try out the bag before you buy. I needed the wider Alpinlite (and Caribou) for my shoulder size. A narrower bag got really claustrophobic feeling.

Dave nailed it.

Unless you are shooting for a specific BPW of sub-6 pounds, do not worry about the extra three ounces and just go for the bag that will allow you to not shiver on those nights when others might be.

He also stated exactly what I believe about the Alpinlite (my WM bag of choice) with it being worth the extra two ounces. Your profile photo appears like you are a slim guy, but if you are at all on the large size, or do not like tight bags, the Alpinlite is very much the WM bag of choice. I went to a local store and put all of their bags on the floor and got inside of each of them and the Alpinlite was the only bag that came close to not making me feel like the bag was too tight.

I should mention that, for me, the extra 6 ounces of the MMULSS#1 is something I do not even think about. It is above and beyond my sleeping bag of choice for sub-30 degree bags. When it comes to sleeping, I just do not care about 6 ounces of additional weight if it means I can sleep in such a luxury bag as what the MBULSS is.

–Abela

I find that clothing makes a big difference.

I have taken a 32 degree bag(WM Summerlite) down well below freezing many times without getting too cold. I will wear thermal pants and a down hooded vest or sweater.

The Summerlite, especially the hood, is not warm enough alone to use much below 40 deg f.
The hood may not be an issue depending on how much hair you have on your head. I have very little so a hooded vest/sweater is important for me

The side benefit of having your clothing act as a large part of you sleeping system is that you don't get cold shock when you get up to pee in the middle of the night.