A fleece is used as what is called a “mid-layer.” You add a fleece when you need something warmer than your t-shirt but something not expected to protect you against wind and rain (which would be your outer layer).
I wrote about fleeces before https://adrr.com/d20/2020/01/31/finding-the-right-fleece/. This is about the fleeces I’ve used and where I am now and takes a different approach.
When you think of a fleece think of a sweat shirt or hoody, only lighter and not cotton. Here are some typical fleeces you will see in a regular store.
On the Appalachian Trail a fleece is worn in colder weather. With the trees blocking the wind I rarely had trouble with a breeze. On the AT I always used full zip fleeces because I would often take my fleece halfway off when it was only kind of cold and I could take the fleece the rest of the way off without taking my pack off.
The above picture is of my first thru-hiking fleece, the Ecolator full-zip. I really liked my Ecolator. It finally wore out which is why I looked for a replacement. It used what is called micro grid which is warmer for the weight than a traditional fleece. In a polyester which holds less water, it is much lighter, and dries much faster than a cotton fleece.
(The next picture lets you see what a microgrid fleece pattern looks like as the Ecolator picture really does not capture that).
At 13 ounces the Ecolator was lighter than the polyester fleeces I had around the house and took on some section hikes. Polyester fleeces are about half the weight of cotton fleeces.
I replaced the Ecolator with a Marmot fleece that has also now been discontinued. The micro grid is clearly displayed in the above picture. It was lighter than the Ecolator and many other fleeces and a great fleece.
For the PCT I made some changes after a while on trail. When it was warmer I sent the fleece home and for colder weather and the Sierras I needed a fleece.
I moved to an Alpha Direct fleece just like Win (Happy) was using. Alpha Direct is a new technology from Polartec, first developed for the military. It is lighter. It is warm and very breathable. But it is only warm when you stop out of the wind or use your rain jacket as a windbreaker.
In motion or in a breeze or the wind it really breathes and sheds heat.
The Timmermade Alpha Direct is not suitable for bushwhacking. It is not a full zip (or any zip at all). It has no pockets. But it is under five ounces. It worked very well on the PCT for me. When I head back out to finish the Pacific Crest Trail I’ll take it with me.
That said, on the AT, everyone carries a fleece. On the Pacific Crest Trail a sizable percentage do without a fleece but often have a wind shirt or other additional layer instead. They also often carry wind pants. I find a fleece easy to use and at less than five ounces rather painless to carry.
Typically I put my fleece on in the morning to start hiking in the cold and take it off once it gets warmer. In cold wind I wear my rain jacket over it.
Anyway. The big current/old fashionable trend on fleeces for the PCT is the “Melly” now lighter and less expensive than it was in version 2.
The new up and coming trend is the raft of Alpha Direct fleeces from garage businesses. Timmermade is what I bought.
Link: Lots of information on Alpha Direct—including its limits and negatives.
Most fleeces have a hood for extra warmth. They don’t need pockets unless used as you would around the house or around town as a primary clothing item. This is especially true if you have a shoulder pouch on your pack for your glasses. Full zip is nice in the right situation but you can hike without it. Saves an ounce or two not to have a zipper.
I found the PCT warmed up more and faster so that I never hiked along half in and half out of my fleece.
The technology keeps improving and they keep getting lighter. Modern fleeces are a long way from 24-28 ounce cotton blend.
Bottom line: I like having a fleece for when the weather is cold. It is an iconic equipment item used by most backpackers in all but warm weather.