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Best Mid-Layer Insulation Apparel

What is the best mid-layer insulation apparel for hikers and backpackers? It depends, of course, on where you hike and the weather conditions you expect to encounter. But first lets define what a mid-layer is to avoid confusion.

A mid-layer insulation top is usually worn over a base layer long sleeve shirt. Its function to provide additional warmth for your upper body, while you’re hiking, in addition to wicking moisture away from your base layer so you won’t be chilled when you stop being active. Moisture, even imperceptible perspiration, that has migrated into your mid-layer, won’t chill you when you stop moving because it’s not in contact with you skin.

100 Weight Fleece

Most hikers use a 100 weight fleece pullover as a mid-layer top because it provides just enough extra warmth when you’re hiking, without being to hot so that you perspire heavily. Fleece also retains its warmth when wet or damp and can be completely “dried” using your body heat if you remain active long enough. The same can’t be said of a merino wool pullover, which takes much longer to dry when it gets damp.

Most Popular 100 Weight Fleece Pullovers

Fleece has the added benefit of being inexpensive and highly durable. You can wash and dry a fleece pullover hundreds of times without it any shrinkage or wear wear and tear. The outdoor industry really shot itself in the foot when they started selling fleece, because it doesn’t wear out over time!

While there are many varieties of branded fleece garments available, you don’t need to buy anything fancy when looking for a 100-weight fleece pullover. Most have a 1/4 or 1/2 zip, which is useful for venting, but other than that, the simpler the better!

Additional Layers

The typical layering “stack” adds a rain-proof and wind proof rain jacket or shell over a fleece pullover, jacket, or vest, followed by a down or synthetic puffy jacket for standing around in during rest breaks or in camp when you’re not moving and generating your own extra body heat.

Many manufacturers have started selling composite and body mapped garments that wrap fleece with a wind proof shell or add extra insulation around the front of a fleece liner garment and not the back. My advice is to avoid these composite garments if you want to save money and stick with the layered approach where each garment performs one function in your layering stack, as described above. When you start mixing layers in one garment it’s utility become very specialized and less adaptable to highly variable conditions.

Reader Feedback

Here’s what Section Hiker readers have to say on the topic of mid-layer insulation clothing.

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  1. I use Outdoor Research Deviator Hoodie for my mid layer when I hike in Smoky National Park. I am hoping that this new mid layer will suffice most of the three season I hike in.

  2. Hum. Living in Germany, traveling here, Ireland, Iceland, Sweden, Portugal.
    So that asks for a variety.. in warmer times, my trusted Icebreaker Merino jacket is heavy, but proven.
    When colder, I have recently added a Patagonia Down jacket to my collection, before I simply used a down west under my Neoshell.

  3. My typical midlayer when hiking in the Midwest and on the AT is usually 100 weight fleece hoody from CORE Concepts under a wind shirt from Canari.

  4. Shawn Wesley Coggins

    What mid-layer clothing articles do you carry?


    Where do you use this system when you hike?

    For all day hikes & all back country country camping trips Note: I forgot the fleece jacket on a backpacking trip at the end of spring this year ~ ended up cutting the trip by a day ! )

    How does your mid-layer insulation change seasonally?

    Fleece Vest during summer months
    Full Fleece Jacket ~ Spring & Fall

  5. I carry an UnderAmor long sleeve compression shirt. I use this when it’s cold at night or when it’s really chilly during the day. I only really backpack during the summer, so my kit doesn’t really change with the seasons.

  6. I hike in northern California, Trinity Alps and Trinity Divide and Lassen. My mid layer is a hooded down parka or a down vest depending on time of year. If it is very warm I just use a mid-weight merino layer. All these options go under a rain shell or wind shell.

  7. I have a variety of merino. Merino is particularly light & absorbent. There are a huge variety of tramps around Hawke’s Bay ranges in New zealand where we explore. In the colder weather I wear 2 merino & in summer exchange for one short sleeved merino.

  8. I use a marmot micro jacket for all 3 seasons in New England . When winter backpacking I have an llbean 15 below jacket .i will add a wind breaker over the jacket depending on wind conditions . The whites of NH can change conditions bs quickly

  9. I hike mainly in Colorado. Because of the high variability in temperature one can encounter during the day, I vary between a mid-weight merino wool long sleeve shirt, an 800 weight down vest, and an REI hiking shirt. As the temperature decreases, I’m more likely to have several of these items on, especially if I’m relatively sedentary around camp.

  10. I hike in Northern California, Oregon, and Washington in the summer months. I wear a Patagonia lightweight wool mid layer. I also use an Exlight down anorak from Montbell when it is very cold in the shoulder months of the hiking season.

  11. I hike in the Rockies and Sierras in the summer, and the Appalachians in Spring and Fall. I use a 100 weight Columbia fleece sweater if expecting temps in the 40s, and a Mountain Hardware down sweater if temps will drop into the low 30s. I also use a Marmot rain/wind jacket for an outer layer.

  12. I hike mostly in Missouri, and a 100 weight fleece is my choice for a mid layer. I find that in the winter, when moving, this is enough, but when I stop for a snack etc, I need to put on the outer layer or get cold!

  13. What kind of mid-layer insulation do you carry on 3 season day hikes or backpacking trips?

    I wear my REI jacket with my merino wool sweater.
    This is my winter hiking attire,
    I wear this in the fall, winter, and early spring.

  14. I’m taking my trusty NASA fleece jacket for a mid layer on my first ever backpacking trip this August in the Rockies. I’ll use my new rain shell on top if I need more.

  15. 100 weight fleece zip up for mid-layer and make sure my other layers are appropriate for variable conditions. I mostly hike in the northern Sierras and foothills.

  16. I’m new to backpacking and have been hiking in warm weather and carry a cap 4 hoody and cap 2 thermal pants. Here in TN I can imagine I will need additional layers for shoulder seasons, and plan on getting a down jacket to use with my Rain jacket.

  17. Hiking/backpacking mainly in the fall and winter I switch between a mid-weight fleece or a lightweight down jacket depending on possible moisture. I’m using Icebreaker merino as base and a Marmot Essence Jacket as a shell. I’ve also got a couple of capable lightweight cycling jackets that work great as adjustable mid layer.

  18. I have a stow-able LLBean synthetic jacket that I like pretty well. I’m a New England hiker, so I need it routinely for my 3 season backpacking trips. Fits well under my rain shell, which is a must!

  19. I wear a fleece pullover for a mid-layer. I hike in California along the coast and Sierra’s. I use a pull over heavier fleece in spring and fall. In summer a lighter weight zip up fleece.

  20. I use a Mountain Hardware Ghost Whisper down jacket.

  21. smartwool tee shirt and a mountbell down jacket….
    that works well foe me.

  22. Sherpa Adventure Gear vest i’ve been carrying for about 4 years now. I hike a lot in more humid climates and the synthetic insulation stays warm, packs small enough and is an awesome sleeping layer when you need just a hair more warmth.

  23. I wear a Patagonia synthetic midlayer that is seen peaking out of my collar in every pic from every season…everywhere!

  24. I usually hike in southern Appalachia. Unless it’s mid-summer I always take a lightweight New Balance or Asics fleece jogging pullover. I usually don’t need it until I get to camp at night. As we move to fall I’ll swap that out for a Mountain Hardware fleece that’s a bit heavier. Typically it still only comes out at camp. As we move into late fall and early winter I bring out the Montbell down jacket for camp and the New Balance pullover gets pulled into duty during the hike.

  25. I use varying weight merino as a mid layer depending on the season. Mostly hike in the Northeast unless I’m traveling, so this does the trick.

  26. I change this layer depending on how cold I think it will be. In warmer weather, I have an UnderArmour lightweight long sleeve shirt with a hood (but not really a hoodie!) that I use. If I expect colder weather, I’ll bring a fleece or actual hoodie along. Nothing I’ve spent a ton of money on – I got a sierra designs fleece on sale, and the hoodie came from the lost and found!
    I’m in the mid-Atlantic, so some precipitation is a concern – but all of these except the hoodie dry rather quickly, and my rain jacket is available to cover them up if needed.

  27. Living in western Washington state, even in summer several layers are sometimes needed. My mid layer for summer is a DIY 100wt fleece, occasionally supplemented with a light long underwear shirt, nylon supplex shirt, ripstop windshirt or Driducks rain jacket. Come September a Costco down jacket is added to my pack and remains there til May.

  28. I do most of my hiking/backpacking in the Sierra Nevada. My mid-layers include a North Face Tech 100 Hybrid micro fleece jacket worn as needed over a base layer ranging from just a T shirt in summer to including an R1 fleece pullover in colder months. The Tech 100 has panels with differing degrees of wind resistance and breathability that make it comfortable to wear under a pack without my stomach/chest/back and arms getting too hot and sweaty on moderate uphill stretches. I then wear a down jacket or synthetic pullover over the Tech 100 at rest stops or in camp during colder conditions. I don’t normally use a mid-layer over my legs.

  29. My primary mid-layer is my BSA Troop fleece jacket, I wear it under a nylon shell in the winter and take it along in the Spring Summer and Fall for the cool mornings. It is also used as a pillow inside a stuff sack. I hike the Tri- State area.

  30. My mid-layer is a long-sleeve polypro shirt, in light or middle weights, depending on temperatures anticipated. From cool or wet summer days hiking (with shorts), down to 30F snowshoeing (under a fleece vest and with nordic pants) out here in the Pacific Northwest, this keeps me in a comfortable temperature zone.

  31. My mid-weight layer is a Marmot Zeus down jacket. It’s over a pound, so its not ultralight, but its compressable and warm. I’d prefer to have a lighter down jacket, but I don’t want to be purchasing new gear every year, so I’m trying to use what I have, even if there is a slight weight penalty. The reason I am willing to carry a heavier layer is because I hike in the high sierra, and it can drop down below 30 degrees F during July, as it did last week. I actually also use this as my mid-layer all four seasons.

  32. Hello, I live and hike mostly in central PA on the Appalachian Trail and Laurel Highlands Trail. In warmer weather I carry my heavier weight Patagonia capilene top (approximately 30 years old and still like new.) During the cooler spring and fall months I carry a 4 year Patagonia lightweight fleece jacket as my mid layer. Thanks!

  33. I use 100 weight fleece 1/4 zip top most of the year. Now that it’s bit cooler here in Australia I got myself a heavier Kuhl alfpaca fleece 1/4 zip top and I combine that with a light weight wind breaker/rain shell on top – very comfy.

  34. I carry a Columbia omni-heat fleece pullover as a mid-layer, with an additional Mountain Hardware Thermostatic jacket for the evenings and cold-weather sleeping.

  35. I use mid weight fleece (misc manufacturers) in the late summer /early fall especially hiking in Maine & NH. Winter season is a mix of fleece, down, and good old wool with a goretex outershell.

  36. I have a wool sweater from EMS that is a great mid-layer. Loved that it has the “moon & mountain” logo.

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