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
- Patagonia R1 Pullover
- Patagonia R1 Hoody
- The North Face TKA 100 Fleece Pullover
- EMS 1/4 Zip Micro Fleece
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!
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.
Here’s what Section Hiker readers have to say on the topic of mid-layer insulation clothing.