Warm Weather Synthetic Sleeping Bags

Reviewed by Bentbrook

The Space Cowboy is a nicely featured 45˚F/7˚C sleeping bag for those seeking a highly compressible, lightweight synthetic sleeping bag option. This bag is readily stuffed into pack crevices or its supplied stuff sack, taking up less room at lower weight than a number of similarly rated bags (albeit at higher price), while providing mummy bag coziness with a draft tube and draft collar for unseasonably cool nights.

In the American South where I live, we’ve had the first few flashes of summer-like heat amid cooler spring weather. It’s enough to encourage trip planning for summer treks. Therm-a-Rest’s Space Cowboy synthetic sleeping bag offers a fully featured summer-weight bag that is well suited for such warm-weather trips. I enjoyed testing the Space Cowboy in summer and early fall, but by layering the Space Cowboy with my Therm-a-Rest Corus HD 35˚F/1.7˚ C quilt, I was able to sleep comfortably in the upper 20s˚F/-2.8 to -1.6˚C, too, a layering option Therm-a-Rest had in mind when designing this sleeping bag.

Read more: Therm-a-Rest Space Cowboy 45F review (1)

Featured review by DLK37086

I can't believe that someone hasn't already reviewed this sleeping bag! These are my GO-TO warm weather bags, and the ones I use more than any of the others! I have two (2) of these bags, and I highly recommend them to anyone looking for a lightweight, warm weather only sleeping bag!

This is the color scheme of the bags that I own. Mine don't look quite as tapered as the manufacturer's stock photo. And mine are not quite as "pretty" anymore, either! Lol. BUT, I purchased these bags in May of 2010, and have used them (with a silk or silk blend liner) on EVERY warm weather trip since then. These bags have gotten more use than all of my other bags combined! So I can confidently say that they are well built and made of durable materials. The standard "legal" tag. The Facts (Yawn): Construction, top and bottom: Mummy sleeping bag, 1 layer Thermo construction Outer/Cover: 100% Nylon [210T Nylon Ripstop] Lining: 100% Nylon [237T Nylon Tactel Taffeta (breathable)] Filling: 100% Polyester [Polydown Soft Polyester] Fill weight: ~160...

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Featured review by Jay Meyer

This has to be the lightest, smallest sleeping bag that you can buy and use for serious hiking/camping/mountaineering. It stuffs down to the size of a football, weighs less than 2 lbs. and dries in a flash. Obviously, there is a compromise: this bag simply will not keep you warm enough to sleep below about 32 f., and anywhere around freezing you really should use it with some form of bivy sack or other supplemental bag. However, it does open the door for some really minimalist hiking possibilities (e.g., multi-day trips with a "day pack"). Well designed and constructed, although its lightweight materials might lessen durability.

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Reviewed by Michael J OBrien

Someone who sleeps with a partner will find this bag has such great design features that they will know the person who designed it loved and hated doing this many times in the past. tThey distilled all these experiences in one great couples bag!

I am 5'8" and weigh 240 lbs and my partner is 5'5 "and weighs 130 lbs. Most of my weight is in the belly, cursed that I am! Considering my proportions, this bag was just a little snug at the mid-section when laying flat next to my partner...not too snug and plenty of room sleeping on our sides as normal. Main Point: I have used zip together bags in the past by Slumberjack. These are very comfortable, but you still have legs parted due to the two bags' foot sections where there is no zipper. Also in spite of the fact there is a large flap to cover the zipper it seems it usually goes the other way thus exposing a cold zipper...and this zipper ends up right on top of you and underneath your partner dead center.

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Reviewed by Theonecanoe

This is a great all-round three-season sleeping bag. It's comfort rated down to 34°f, and compresses really well. The outer shell is waterproof, and even though it is a mummy style sleeping bag there is plenty of room inside to move around and get comfortable.

The Mountain Hardwear Lamina Z Spark sleeping bag is a 3-season sleeping bag that is comfort rated down to a temperature of 34°f/1°c.  I have used this on several trips with temperatures dropping as low as 3°c, and felt no chills at all while using this sleeping bag.   This sleeping bag weighs in at a reasonable 1 kg, that's only 2.2 lbs., and it compresses very well so it does not take up too much room. For a mummy style bag, there is plenty of room inside with lots of shoulder room and a very large foot box.   Please check out my review video to see all the features of this excellent sleeping bag.  Thanks.       -Wayne  

Read more: Mountain Hardwear Lamina Z Spark 34 review (1)

Featured review by Former User

I love this bag. I also have another colder weather bag but just keep using this one.  If really colder and below the bag rating I use a liner. I never used to use mummy bags but this one works out. Not quite as restricted as some other mummy bags which works for me and still keeps me warm. It is a synthetic bag so loft is not quite as good as a down of equal thermal value but I love it.  A little more reliable in wetter or damper conditions and I pull it out as soon as the tent is set and the lofts comes back soon there after.

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Featured review by Ministercreek

Excellent bag! This bag's fill (The Backside's X-fibre) is very close to goose down in terms of weight and performance. The bag stuffs to the size of a football. Since I am allergic to down the X-fibre insulation is just perfect for me. I purchased this bag to take the chill out of Wisconsin's cool nights which are in the 40+ degree range. The Backsider bag is just the ticket for a comfortable nights sleep! This bag is very soft, the inside liner that is. It is polyester with an diamond ripstop outer shell.

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Featured review by Shannon Guy

The Lodgepole's roomy, oversized fit will allow you to sprawl out while keeping you toasty between 40-50 degrees with its quick-warming brushed liner, cozy fleece collar, and fleece-lined footbox.

I'm 5'3" and I am a stomach sleeper. I like to have a knee up and in this bag, I can actually put my knee up. This is the biggest plus about this sleeping bag. The fleece collar is great too. I used this in my camper with the ac on 66° so I was able to use it and not sweat to death. The zipper worked great—I hate it when it gets caught over and over again in itself. 

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Reviewed by Mikemorrow

There seams to be some confusion with the High Peak temp ratings. I was told that this was rated at 21 degrees. Well...it is. That is the temp you will die of hypothermia. As I was looking for a warm weather bag of +40 degrees and needed a light weight bag for summer use, I knew that there is no sleeping bag on the market that only weighs 13.44 oz that could be a 21 degree bag. Looking though the specs I soon realized that its true rating was 52 degrees. This is the temp that one will be very comfortable.

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Featured review by Mike068

I have used this bag on several trips through the summer months while sleeping in lean-to's and tents. I will say this it is a very nice bag. Also it's lighter weight than most synthetic sleeping bags. It kept me very warm in summer temps I was a tad chilly once but the temp dropped to the low 40's high 30's but it was nothing drastic I just threw on my t-shirt, socks and I was fine. It's very spacious inside the bag as I like to be able to move around a bit it has the perfect size foot box so you are not trying to keep a large area warm.

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