Wool—Wool can be very useful as a mid-layer, though you may be too hot wearing a woolen top and too cold taking it off. Heavy wool is best used in colder environments or when inactive for extended periods of time. Most wool clothing was replaced by fleece when it became available.

Outer Layer

The outer layer of clothes, often referred to as the “shell layer,” should be water and windproof, be resistant to wear and tear, and allow the escape of moisture (sweat). Most of these properties can be combined in modern jackets made out of materials coated with a membrane. Gore-Tex, Pertex, eVent and other brands offer this option. These membranes can be coated onto many different types of fabric, so you should be able to find a fabric that suits you most depending on your required comfort level and tear/abrasion resistance.

It is best to avoid rubbers or plastics. Though they are perfectly water- and windproof, they do not allow sweat to evaporate and will make you wet (and ultimately cold) from sweat. Breathable fabrics such as the ones made by the brand names mentioned above still need regular treatment with water-repelling sprays. These sprays are not meant to stop water from penetrating the cloth (as the membrane is waterproof), but to ensure liquid forms “beads” and runs off, leaving the pores of the membrane clear to allow the evaporation of sweat.

As an aside, many companies now produce outdoor coats and jackets with a removable fleece liner, which allows you further flexibility to increase or decrease heat retention. When gauging size, you’ll want to be sure that your shell layer covers you entirely with no gaps in protection, even when stretching or bending over.

Personally, for a trip into the outdoors, I like to wear a long-sleeve merino wool base layer with a comfy cotton T-shirt over the top. As an outer layer, I use a fleece-lined waterproof jacket. Then, for colder days, I add a fleece or cotton sweater, while for warmer days, I lose the fleece lining of the jacket and perhaps the merino wool base layer. Of course, none of these layers is set in stone, I simply pick and mix as conditions require.

The trick is to not wear one super-thick layer trying to do every job, but a large array of thin layers, each with its own advantages, which can then be added onto or subtracted from to gain the protection you need.

Of course, it may very well happen that you are caught out with too few clothes on. One simple trick to adding insulative properties to your clothes in an emergency is simply to pull your socks over the trouser legs, tuck your T-shirt into your belt and fill your trouser legs and shirt with crumpled-up newspaper, car seat foam, (dry, non-toxic) leaves, or whatever else you can get your hands on. Just be sure to avoid stinging nettles or holly!

Other Clothing Items

Other clothing items to consider are socks, shoes or boots, gloves and hats.

Socks—Just like other clothes, socks come in a large variety of materials. Most outdoor socks are made using a blend of materials, such as merino wool combined with nylon or other artificial fibers. Many companies also produce their socks without any seams or with seams that are relocated to improve comfort and reduce blisters. It is worth testing several different types of socks to find ones you’re comfortable with, especially since they come in different weights. It is now even possible to purchase waterproof yet breathable socks, though I have never tried them, so I don’t know how comfortable or successful they are. Watch out for socks being too tight around the leg, as this can reduce blood flow. Multiple pairs of socks can be worn, assuming your footwear is spacious enough. One thing to keep in mind is that your feet will generally always get damp when engaging in any length of a hike. Boots will never be able to allow all of the perspiration being generated by the foot through, so pick your socks with this in mind.

Shoes and boots—As far as insulation goes, look for an integrated package of the mid-layer and outer layer of the clothes we discussed earlier: warming, moisture-wicking inside and waterproof and durable outside. Manufacturers produce a wide variety of outdoor footwear. Many people will pick lighter shoes for walking and heavier boots for hiking and camping. If you can only pick one pair, I would stick with a good three-season boot.

Within these ranges of footwear, you generally have a choice between fabric or leather boots. Fabric boots are usually lighter as they are made out of a combination of suede and synthetic fibers combined with some form of breathable lining, such as Gore-Tex laminated fabric. I find shoes and boots made out of this material are generally warmer, though they tend to offer less protection upon impact with branches, rocks, etc. They also tend to be a bit more difficult to maintain well.

Leather boots are somewhat heavier and can be a little bit colder, but are generally longer lasting, especially if well maintained with leather wax or similar treatment.

Being particular about the boots you buy is well worth it, as you will have to make do with the pair you choose to wear, whereas clothing can be changed to suit.

Apart from choosing the type of boot, achieving the best fit is also important if not more so. I strongly recommend bringing a sample pair of your usual outdoor socks with you for fitting shoes. While wearing the socks and standing, place your foot in the boot and, leaving the laces untied, slide your foot forward so you touch the front of the boot with your toes. If you can slide a finger into the boot behind your heel without any force, that’s the first indication that you’ve found the ideal size. The next test is to stand as you normally would in the shoe or boot, tie up the laces and walk around. You may find your heel lifting slightly from the sole of the boot, but provided that it is no more than about a finger’s width, this is normal and will often stop happening once the shoes or boots get worn in. Other than that, the boot should feel comfortable, your foot should feel well supported and your toes should have freedom to move about a bit.

It is very important not to buy shoes that are too small, though you can usually get away with buying a pair that’s slightly larger than ideal.

For extremely cold conditions, it is important to pick footwear with flexible soles and a maximum amount of room inside for the toes so the foot can move about. Picking footwear which allows the foot to flex naturally while walking is very helpful when trying to avoid cold toes. It may even be worth it to make your own. At home I have a pair of self-made moose leather and canvas boots/moccasins lined with felt, which are far more successful keeping my feet warm at –50°F than any other boot or shoe I have ever tried (so long as they’re kept dry).

Gloves—Here I look for similar properties as the shoes. A soft, warm and comfortable inside and a waterproof, durable outside. There are several manufacturers out there such as Sealskinz or Dexshell, who produce waterproof yet breathable gloves. On occasion, I use such gloves and wear mittens over the top when not using my hands much in extreme cold. When I require the dexterity of my fingers, I simply temporarily remove the mittens. Again, making sure that your gloves are roomy enough for you to be able to move your fingers around is important as it helps stop your fingers from getting cold and stiff. It’s also possible to get warm mittens where all fingers except the index finger and thumb are together, combining warm mitten-like conditions with dexterity.

Hats—You can’t beat a simple fleece or wool hat combined with the use of a waterproof coat/hood when required. In extreme cold, faux fur or fur-lined hoods and hats are excellent choices. You should also consider having a good scarf available for outings. My personal favorite is a tubular scarf that pulls over the head and contains extra cloth at the bottom of the “tube” to cover my back and chest, just at the places where drafts can sometimes get in via the coat zipper.