My golden rule for selecting materials for a nice long wilderness trip is clothing first! I am very fortuned that I have been traveled up north a great part of my life and that will helps me a lot to survive extremely weather conditions. My biggest outdoor experience I had at age 18 when I stayed 4 months in the arctic tundra of Finland far away from the nearest road. It was very spectacular and no school is teaching you any of those skills and that's actually very sad. Maybe it would bring people closer to nature and let them respect wildlife much better as well. When my wife started with fly-fishing in 1991 the first equipment I was looking for was excellent or first class clothing. I knew very well that when she wouldn't feel comfortably, she will quit fishing pretty soon. At that time I often had been visiting the northern parts Norway, Sweden and Finland and the weather conditions in Scandinavia can be very unpredictable. It can be freezing at night, chilly in the early morning and cold in the evening while at the same time the temperature can be quite warm during daytime. It can be windy, foggy, raining, snowing but also really hot and so you need a great variety of clothing. My experiences with clothing for fishing are mainly based on Scandinavian and Canadian weather conditions but many people fish early spring and late autumn as well. In those seasons weather easily can go mad in many other well known fishing areas not as far up where I usual went. 

Although, we had most of the time excellent summer weather in northern Canada it is not much different from Scandinavia. If the clothing isn't perfect you better stop fishing right away. When only one person in a group doesn't feel comfortable it can spoil the fishing for all the others members too! I have seen this many times, especially when people visiting wild and unknown places. Many times; cold feet, freezing hands and wet clothing let people decide to stop fishing and this is very distressing because it really is not necessary with all the excellent clothing available today. If not prepared well you surely will get into some nasty problems. I learned my lessons very well so in my workshops and classes I put a lot of effort in the chapter clothing. I am a big fan of Patagonia clothing and after using it for more then 15 years I know exactly what I really need and must use. Patagonia has a marvelous reputation when it come to outdoor clothing. Let me give you a few samples:

Rain
Nobody likes to fish in poring rain so a first class wind and waterproof jacket (for example the SST jacket) must have the highest priority for every fly fisher. We all like to travel light so the jacket must be able to compress easily so that you can keep it in the back of your fly fishing vest without loosing comfort while casting and hiking or at times when the jacket is not really needed. My wife tested a new wind and waterproof jacket that has a lot of stretch in it and she was very pleased with it! Woman usual prefer a longer jacked because they don't like it to wade deep and also prefer hip waders more often. 

A light wind and waterproof jacket prevents you well from getting wet but it doesn't protect you from cold. For example: A lot of people underestimate the use of cortex. It's perfect for rain and wind but don't protect you from cold. The most perfect combination will be a light waterproof jacket with a nice fleece pullover or jacket underneath. When cold get deep into your bones you never will be able to warm yourself anymore and you have to return to your camp or make a nice fire to get away from it. Unfortunately a campfire is just a temporarily solution. Your wind and waterproof jacket must be chosen well. You will need a hood on the jacked too. It will not only prevent rain dropping into your back but also will keep your neck warm and prevent you from bug attacks! Using a nice cap or hat underneath the hood will be a good solution to keep the visibility high during fishing. Especially in the rain and a hood also will prevent the rain dropping on your glasses or into your eyes. A hat or cap will be very useful in sunny conditions too. It will keep away direct reflections from the sun and makes it possible to use Polaroid sun glasses better. 

Wind
There are many people who don't like wind or windy conditions. I come from a country where there is a lot wind and that makes a lot of things much easier for me. I also fish frequently in Denmark where it can be real windy too. I am used to cast into the wind but I also know how to protect myself well against nature elements. 

Fishing in cold windy conditions can lead to muscle pain easily and makes your bones really cold. That all will reduce comfort and smooth casting and then a fly fisher can loose his concentration easily. For wind protection there is wonderful clothing nowadays. There are even wind protected or windproof fleece jackets and once you have used one you surly will be hooked. I love fleece because it keeps you mobile and makes casting easier and that's exactly what a fly fisher needs. A windproof fleece jacket will be my second personal choice beside a wind and waterproof rain jacket. I have tried the Retro X for quite some time and when the rain is not too bad I even don't use my rain jacket at all. Good quality fleece still will protect your body well even when it's getting wet. 
 

People also underestimate the power of boats. When you need a boat trip to reach your fishing waters you have to remember that you have to get back too. I have seen people wearing T-shirts only because the weather was just so nice. In this particular group, none of them had taken extra clothing with them. They drove over 10 miles and the weather changed and before they got back most of them were in freezing cold. In a boat you always need wind protected clothing because the air levels just above the water and speed of the boat will make you chilly easier then you ever would expect! 

Cold
There is nothing more frustrating then leaving your fishing spot because people are cold. I have done several classes and workshops with women and they get cold feet and hands much quicker then men. (maybe therefore they are more lucky to catch the real big specimen easier) Women are great fly fisher and when they hit a good fishing spot they hardly can stop and easily will forget the power of nature elements. A pair of thermo socks is required if you want to be sure to keep your feet warm. If wading in cold water (and I can assure you that most of the waters in the north are pretty cold) good underwear is indispensable. In the north you have daylight almost whole day but the sun looses it's power quickly when the twilight starts. When you fish high above sea level temperature easily can drop until just above freezing. It actually happens rather quickly too because the sunset can be pretty long and as soon the sun has been fade away mostly every body get chilly right away. I usual start to change clothes as soon the sky turns into fire. 

Nice temperatures
When the weather is nice I protect myself too. I always use a long sleeved polo shirt. It protects me from sunburn and also keeps some nasty bugs away. Be sure your shirt protects against mosquito bites. 

Special fly-fishing clothing 
I prefer wading shoes especially when long hikes are needed to reach your fishing spots or searching for fish. My choice is a wading shoe with steel studs in the sole. There are wonderful waders available those days. Breathable waders seems to be very popular nowadays but for the icy waters in the north I still prefer neoprene and rather thick too. The waters are very cold and 4,5mm is required when you are used to stay in the water for long time. Underneath my waders I always wear special underwear, it's not only easier to get into the waders but also give you an excellent protection against cold-water temperatures. I use thermo socks underneath my waders and always use a second pair of old socks over my wader. That trick works well and it really takes longer before the feet get really cold. It also protects the feet of the wader much longer and also keeps the gravel outside. A fly fishing vest is indispensable.