Everything above is sage advice. But I offer two qualifiers:
1. Layering is a good replacement for single-purpose items. Keeping cold OUT is as good as keeping heat IN.
2. Warm and wet is good. Cold and wet is always bad.
Many folks find that a full zip fleece, over a long sleeve polyester/nylon/synthetic shirt, and all under a wind resistant water resistant outer layer (parka) is a valid sandwich scheme for keeping heat in and wet out. You will still get soaked from perspiration, but that is warm. it is the layering a movement that is key to comfort and safety here.
I usually do my Caminos from April to June, as I like the new flowers and green fields. However, those of you who have done this know that you are likely to have some sort of precipitation almost every day. Also, you WILL encounter snow at elevations over about 700 meters.
After much experimentation, and mailing several boxes of extra stuff to Ivar in Santiago, my clothing kit has stopped varying after three Caminos. The list below can be used about 10 months of the year, at least IMHO. I exclude January and February, simply because I have less knowledge of these periods.
My layer-planned outer wear consists of (from the skin out):
Upper:
- Underarmour (or similar) short-sleeve synthetic polo / golf shirt. (1 worn + 2 packed)
- North Face long-sleeve, full-front zip 100 Series Polar Tech fleece with collar (no hood) (x1)
- Marmot long-sleeve windproof and water proof rain parka, with hood and LONG pit zips (x1)
- Sea-to-Summit Siliconized Nylon poncho. Covers everything except my lower legs. (x1)
- Outdoors Research ventilated "Swift" ball cap. Fine for casual wear and great for become a "bill" under a poncho. AND
- North Face lightweight mesh-ventilated "bucket style" sun hat with wide brim and neck-cord, a must on windy days.
I now carry a compressed, synthetic fill, insulated vest for evening wear, or as an added layer (over the fleece) in the event of a weather emergency. Compressed it is about the size of a very small orange (smaller than a fist). It weighs about 450 gm.
I also carry a folded, foil emergency blanket for ultra-emergencies, or encountering an injured pilgrim who needs rewarming - FAST. It is the size of a packet of cigarettes and about as heavy. But, I have seen these foil blankets save lives. So, point taken...
In one, rear hip pocket of my pants, I also carry a Buff, for neck and head protection. In 2014, I found that this also worked great as an expedient compression bandage (packet of tissues held in place by the Buff) on my head.
Note: I fell over a fence with my rucksack on. Memo to self: (a) if you need to hop a fence, you ARE going the wrong way; and (b) remove rucksack BEFORE attempting to hop said fence...duh!?!?
Lower:
- Microfiber liner socks, navy blue, black or dark grey (hides stains) (1 worn + 2 packed)
- Merino wool "Smart-Wool" ankle height hiking socks (1 worn + 2 packed)
- Keen Targhee II Gore Tex lined, "waterproof" mid-high hiking boots (with prescription orthotic insoles)
- Exofficio boxer shorts (the loose fit kind) (1 worn + 2 packed)
- 100 % Nylon, windproof and water resistant, cargo-style hiking pants, with zip off legs. (1 worn, 1 packed)
- Nylon web belt with money-belt feature. I prefer the zip money belt to a "gut pouch / wallet." (x1)
My pants have a second, vertical zip to allow removing wet and muddy lowers without having to remove boots. I can wash the lowers separately or rinse in any puddle or body or water that is available and they dry in about one-hour after wringing. Just FYI, they are "Sahara" model slacks from REI in the US.
I do not use gaiters because: they are added weight, and my nylon zip-off lowers serve the same function and can easily be removed for washing. Also, you do not lose a lot of heat from your lower legs. So, once you get used to having wet pants legs, there should not be a problem.
Finally, I carry a liter / quart sized zip lock bag containing my "cold weather kit." In this bag are:
- a lime yellow (day-glo) synthetic head beanie, for when a Buff and ball cap simply are not enough; and
- a pair of microfiber "runner's gloves" from my local discount store (Target or Walmart). Champion make a good line of these.
The hat is to retain body heat. The gloves are to facilitate using my poles in cold weather. I have both bright line-yellow and grey colors. I flip a coin to determine which I take.
I prefer synthetic fibers to natural fibers because they:
- insulate when wet (so does wool),
- are relatively lightweight when wet (not so with wool),
- do not stink when wet (wool does), and
- dry relatively fast (not so with wool).
I understand and respect that many pilgrims will prefer natural fibers. I find that, excluding cushioning for my feet, wool does not provide the same utility or value as does synthetic fibers.
Having sorted the clothes I wear, I am now struggling with everything else. My ongoing experiments are with various methods for toting all this stuff. I started with a 48 liter rucksack in 2013, and again in 2014, and 2015. For 2016, I am trying to get it down to a 35-liter rucksack. The more volume you have, the greater the tendency for stuff to fill that void. Plus, excepting dead space, EVERYTHING weighs something...
My latest find, based on a Forum recommendation is a set of Ribz front bags. In test fitting and loading they appear to work very well. We shall see....
I hope this helps the dialog.