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Good summer JMT sleeping bag?
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Alexander Laws
(goldenmeanie) - F

Locale: Los Angeles
Good summer JMT sleeping bag? on 09/21/2009 10:39:53 MDT Print View

Hello all! Planning a John Muir Trail trip for next summer and am looking for a new down sleeping bag for the trip. I was wondering which temperature bag would be appropriate for the trip in the summer months of mid july to august. I thought I might be able to pass with a 40 degree down bag and maybe use layering (long undies) when colder temps are encountered... but I am wondering if a 15 degree bag will be a best "all temps encountered" bag. obviously, I prefer to keep it as light as possible, but I do dig the mummy bags rather than quilts, etc.

I do plan on sleeping in a Gossamer Gear 'The One' shelter and will use a insulated ground pad... these should contribute to warmth factor.
Any thoughts from anyone with experience on the JMT in the summer months?

Thank you!!!

First Last
(snusmumriken) - F

Locale: SF Bay Area
Somewhere inbetween on 09/21/2009 10:55:20 MDT Print View

You might not have any nights below freezing - then again you might have a few.
I've done the trail a couple of times (July and August) and took a 15 degree down bag. It was warmer than I needed, but I would have been too cold in a 40 degree.

I'd suggest something in the 20-30 degree range.

Lori P
(lori999) - F

Locale: Central Valley
re: JMT in summer on 09/21/2009 11:00:00 MDT Print View

If the first week of August is still summer... we experienced freezing temps a couple nights and had snow falling on us at one point (between Reds Meadow and Shadow Lake). Not ongoing, accumulating snow, but yeah - snow.

I'd take something rated between 20-30F for comfort's sake.

Jeff Patrick
(callmeammo) - F

Locale: Sacramento
golite ultra 20 on 09/21/2009 11:23:51 MDT Print View

get the golite ultra 20. Lightweight, good to about 30, and you can air out on days when its too hot.

Jonathan Ryan
(Jkrew81) - F - M

Locale: White Mtns
Re: Good summer JMT sleeping bag? on 09/21/2009 12:12:45 MDT Print View

anything warmer than a 30 deg bag will keep you happy and warm. When my wife and I were out there we shared a warm 2 person sleeping quilt in a 2 person bivy and still needed our insulating jackets and long underwear to keep comfortable. The Golite Ultra 20 with a good down hooded jacket would prob work well.

Kevin Yang
(kjyang) - F
Montbell Down Hugger #3 on 09/21/2009 12:43:07 MDT Print View

I did the JMT late August/early Sept this year and used the Montbell Down Hugger #3, a 30 degree bag. For many nights it was OK, I got about 5-6 nights around or below 32 degrees above 10k feet and it wasn't warm enough for me. I had to sleep wearing my fleece. It is an excellent bag but I would suggest a 20 degree bag.

Jay Wilkerson
(Creachen) - MLife

Locale: East Bay
Good summer JMT sleeping bag? on 09/21/2009 12:43:51 MDT Print View

I did the first half of the JMT to VVR with a WM Linelite 40* bag with little problems at all (some times cold). I then change out my bag to a WM Superlite 20* bag for the much higher elevations that you will encounter. You will for sure be sleeping at some very HIGH elevations and Katabatic Air will always be a lurking. It is better to be safe then sorry---When I do the JMT again I will take a 20* bag the entire length.


David T
(DaveT) - F
. on 09/21/2009 13:13:11 MDT Print View


Edited by DaveT on 06/16/2015 21:35:08 MDT.

Alexander Laws
(goldenmeanie) - F

Locale: Los Angeles
thought so... on 09/21/2009 13:26:50 MDT Print View

Thank you all for the suggestions! I had a feeling that a 20 degree bag was probably in order... Much better safe than sorry! And the shopping begins ;)

Don Wilson
(don) - MLife

Locale: Koyukuk River, Alaska
re: Thought so on 09/21/2009 13:34:27 MDT Print View

I'd say go with a 30 degree bag, and wear more clothes at night if you need it. A 20 degree bag is overkiil on the JMT in summer - assuming you use your clothes as part of your sleep system. JMO.

Alexander Laws
(goldenmeanie) - F

Locale: Los Angeles
bagged on 09/21/2009 13:56:57 MDT Print View

Maybe a bag like the Mont-Bell U.L. Super Stretch #2 800 fill? 25 degrees and weighs 1 lb. 12 oz. and sells for $259 right now...

I also looked at a Golite adrenaline... near same specs and price as above...
and the Golite ultra 20... seems more like a quilt that will have to fasten around the sleep pad. Not sure about that. light though.

So maybe a 3o degree with polypropylene or silk long underwear for when real cold hits, or just be safe with a 20-25 degree bag AND polypropylene /silk long underwear?

Don't want overkill nor unnecessary weight... but also don't want to be caught with my pants down... in the cold that is.

Jim MacDiarmid
(jrmacd) - MLife
Re: bagged on 09/21/2009 14:31:48 MDT Print View

Get a 30 degree bag that's a couple ounces lighter than a 20 degree bag, and boost it with the MB UL Down Inner Parka (or similar) that you should be carrying anyways for cold nights.

In the Sierra summer months, altitudes 6,0000'-10,5000', I found a combination of a 30 degree bag + Montbell UL Down Inner Parka to be sufficient. That's including a night in the teens and a night in the 20s. (In a tent) I was definitely chilly on the teens night at about 4am, but it didn't keep me awake.

It really is only a few ounces difference between a 20 or 30 degree bag, so it's your choice. I figure I'm carrying the jacket anyways, so why not use it to the fullest.

As far as bags, Marmot and Montbell both make really nice bags that go on sale frequently, but you can't top a Western Mountaineering Megalite or Summerlite (30 degrees) or a Nunatak quilt, they're just pricey.

Frank Deland

Locale: On the AT in VA
20 degree bag on 09/21/2009 14:53:48 MDT Print View

August 10-24,2009, I used a 20 degree WM Ultralite bag, Big A.Exped mattress and a few nights a homemade bivy, silnylon bottom and Momentum top. Was glad to have this combo for warmth. There was a glaze of ice in the morning on my SMD Wild Oasis shelter along side Guitar Lake. A few nights I slept with the bag mostly open. Just be prepared for the cold. I had hail one PM.
BTW The scenery is beautiful and ever changing.

Alexander Laws
(goldenmeanie) - F

Locale: Los Angeles
parka and bag on 09/21/2009 15:31:31 MDT Print View

Great suggestion on the MB UL Down Inner Parka with a 30 degree bag... I figured I would need a light down parka for the chilly nights/mornings. I don't have one as of yet...

Scott Bentz
(scottbentz) - MLife

Locale: Southern California
30 Deg. Bag + Down Jacket on 09/21/2009 16:43:58 MDT Print View

I was going to take my MontBell SS #5 (40º) and got nervous so I bought a Western Mountaineering Summerlite (32º) bag for my JMT hike. I thought the warmer bag would be okay because I was also using a MontBell UL Down Inner Jacket. However, I had an e-mail from someone that said they had a few nights at 9,200 ft. that got down to 26º. We had 2 nights where I saw frost on the ground in the morning at approx. 9,000 ft.

Looking back, I was glad I went ahead and got another bag. I never slept with my jacket on but my new bag only weighs 3 oz. more than my 40º bag. Considering all that could happen in the Sierras during the summer, wind, snow, heat, rain, etc. I think a 30º min. bag is prudent. The only problem I see is if you have to spend the first night in Yosemite Valley since a 30º bag is quite warm. We just unzip and use like a quilt.

Alexander Laws
(goldenmeanie) - F

Locale: Los Angeles
bagged on 09/21/2009 17:46:47 MDT Print View

Wow... the MB UL Spiral Down Hugger #3 weighs in at 1lb. 3 oz. as a 30 degree rating... Seems very comparable to the Western Mountaineering SummerLite, and for $219.


Jim MacDiarmid
(jrmacd) - MLife
Re: bagged on 09/21/2009 18:47:20 MDT Print View

I happen to have owned both of those bags this summer before settling on a Nunatak quilt. I used the MB 3 times and the WM twice.

The big difference is the interior space of the bag. I'm 5'10", 175lbs with broad-ish shoulders for my size. The Summerlite is a narrow bag and that turns a lot of people off. I was fine in the shoulder region. I could wear a MB Alpine light down jacket in it without compressing the jacket. Where I would've liked more rooms is in the knee region, as I'm a side-sleeper.

The MB bag is plenty wide throughout. I liked it alot and probably would've ended up keeping it over the Summerlite if I hadn't got the quilt.

A couple things about the MB bag though. MB currently sizes their bags differently than everyone else. Regular fits up to 5'10" and the long up to 6'4". This vs 6' and 6'6" with everyone else. So at 5'10", I was told by a knowledgable salesperson I needed a long. That's a lot of extra foot space(and dead air), and it certainly had my feet a bit colder than the Summerlite on similar temperature nights. Not cold, just cooler. I've read MB is standardizing their lengths soon.

Also, the MB doesn't have a full zip. (The Summerlite does) It's a 3/4 or so zip, stopping 26" from the bottom in my long, which complicates quilting it in warmer temps. My feet get warm and I like to be able to poke them out once in awhile.

I never quite hit 30 degrees with either bag. Probably bottomed out at 40 in the Summerlite and I was quilting it to stay cool. In the MB bag it got cold enough to have a little bit of frost in my tent. That night was on snow as well, and I was definitely at the limit of the bag unaided by a jacket. The Summerlite is probably a bit warmer due to the narrower cut (less dead air to heat)

But for the weight, comfort and price, I'd have chosen the MB if not for my Nunatak Arc Specialist.

The WM Megalite is very popular here for 5 oz more than the Summerlite and even more interior room than the MB Spiral Down.

Alexander Laws
(goldenmeanie) - F

Locale: Los Angeles
Thanks James! on 09/21/2009 19:52:32 MDT Print View

Thank you for that info James!

I am also 5'10" and weigh about 140lb., so I would assume fit into either bag. I am a total back sleeper though, so a narrow cut wouldn't be all that bad in my case... as I wake up just as I go down, on my back in the casket position.

I must admit, you guys do have me curious about quilts... but I am gun-shy seeing as I am so used to a toasty mummy bag...

Jeff Patrick
(callmeammo) - F

Locale: Sacramento
summerlite on 09/21/2009 20:02:27 MDT Print View

The biggest benefits of a quilt in my opinion are freedom of movement and being able to vent.
If you don't need the space since you don't move, go with the summerlite. Its continuously baffled so you can adjust where the down is, meaning that if it is too hot you can move the down from the top of the bag to the bottom which will raise the temperature you'll be comfortable at. At least thats my understanding.

Raymond Estrella
(rayestrella) - MLife

Locale: Northern Minnesota
Good summer JMT sleeping bag on 09/21/2009 21:05:50 MDT Print View

I have done it a couple times and am on pieces and in the area a lot. I suggest bringing a 20 F bag for that long a hike as there is no way you can get an accurate forecast for the entire time you will be there. I have seen in drop into the 20s F in August with snow. I have seen it go below freezing in every month of the summer.

A 20 F bag (or 25 like the MB you are looking at) is a good compromise. If it gets too hot, open it up.

That said I used a GoLite Ultra 20 quilt all this summer and just bought a Nunatak Arc Alpinist to use up north this fall. I am hooked on the quilts now.