To keep nice and warm in the snow, the first thing most people think about is getting hold of a nice warm ski jacket and some warm ski pants. Sure, these are important but it is a much better idea to consider your entire outfit as a layering system, with each layer working with the others for optimum comfort, warmth and performance. This way you can get all of the warmth you need, without looking like a Michelin Man! Snowboarding and skiing both involve a huge amount of physical exertion - so you can get very hot and sweaty, followed by periods of doing nothing sitting on a chair or drag lift - where you could be exposed to massive wind chill and freezing cold conditions. Your clothing needs to perform in a huge variety of conditions - which is why it is so important to plan your layering system and not simply to wrap up as warm as possible (like your mum might have you believe!).
Snowboard and ski base layers come in a variety of man made or natural fibers, the pros and cons of which are discussed in a different article. I like to wear a merino wool base layer set ie thermal pants and a thermal top. These should be close fitting and figure hugging - they are fairly elastic so they do naturally tend to fit tight. Choose the thickest wool possible for maximum warmth. The wool thickness is quoted by most brands in grammes. Your base layer should be figure hugging and in contact with your skin so sweat can be wicked away. The body sweats to cool down so sweat remaining on your skin and not wicked away is not good if you want to stay warm. In snowy cold conditions, sitting on a chair lift for example, your sweat can actually freeze. This is no joke. It is therefore important to make sure your thermals are good quality, high wicking and figure hugging.
Next, pick out a mid layer. It is important to choose one which works in conjunction with your base layer. The sweat wicked away by your base layer needs to go somewhere - so a close fitting high wicking mid layer also makes a lot of sense. Again, my personal preference if for wool - it just feels so nice and snug. I am not talking about a woolly jumper knitted by your granny! These days proper technical mid layers have an extremely fine knit designed to wick away sweat so do not even look like wool.
Your base and mid layers together should be light and thin so as not to restrict movement and not feel bulky or uncomfortable.
For most people in most conditions all you need is a base layer, a mid layer and an outer ski / snowboard jacket. You will be plenty warm enough but, if you suffer from the cold or if you are skiing in North America, where conditions can be a lot colder than in Europe, you will also need a second mid layer. For the second mid layer, your sweat has long since left your skin so the emphasis switches to materials which hold pockets of air. These air pockets are what provide the insulation. Light fluffy fleeces are ideal, as are puffa jackets, vests or gilets - made using either goose down or man made fibres. Almost by definition, mid layers which contain lots of air tend to be bulky so your movement will now be a little more restricted. Some 2nd mid layers can also be used instead of a ski jacket. They will not have any of the waterproof properties of a proper jacket or outer layer but it does not rain often when you snowboard or ski and if you head straight for the bar, as Phil Collins said, no jacket required! Seriously, lots of people like to ride or ski without a traditional ski jacket if the weather conditions permit.
Finally, ignore Phil Collins, a jacket IS required. A good outer layer protects you from wind and rain. You do not need a ski jacket which keeps you warm if you are going for a 4 layer system, a thin outer shell is all you need to keep the wind off and the rain out. Most of the time I use a 3 layer system where my outer jacket is an also an uninsulated shell because I find this plenty warm enough most of the time. There are, however, plenty of insulated jackets on the market. You might choose an insulated outer layer if you do not have a second mid layer or if you suffer from cold or if you ski in extreme cold conditions. The down side is that these jackets tend to be big, bulky and heavy. You can also very easily overheat wearing them. The sad truth is that they tend to be bought by beginners because they think they'll get cold in the snow, not realising just how much physical exertion is involved skiing and boarding and how sunny it can be in the mountains.
By now, you will hopefully have realised that a 4 layer system is best. Most of the time, you will only use 3 layers but you can easily add or remove a layer should weather conditions change. This is not possible if you choose a big, heavy, nice and warm outer jacket - keep this for apres ski and walking around the ski resort at night - where it really does get cold.
If you have a pair of insulated snowboard /ski pants you can sometimes get away without wearing a thermal base layer but you will be more comfortable wearing thermals next to your skin. If you wear a pair of thermal base layer pants, your actual snowboard or ski pants do not need to be insulated, unless you suffer from the cold or are skiing in extremely cold conditions, because most people will be plenty warm enough.
Do not forget you will also need:
• Liner Gloves - if you suffer from the cold, you can layer up your hands as well and wick away the sweat
• Disposable hand warmers
• High quality snowboard / ski socks to wick away sweat in the same way as your base layers do
•Liner socks - particularly useful if you have sweaty feet, in which case you probably also want boot bananas
• Disposable foot warmers
• Boot drier/warmer - your feet will never warm up if you start the day wearing cold damp boots.
•Balaclava - not for robbing a bank but for protecting your face from bitingly cold wind. Most will fit neatly under you ski / snowboard helmet or ski hat.
•Ski Snowboard Face Mask - instead of a full balaclava, some people prefer a face mask to protect the neck and lower part of the face. Airhole, with their neat breathing hole are market leaders.
• Ski Hat - if you are wearing a helmet, you will still need a warm hat for when not on the slopes
• Ski / Snowboard Helmet - a no brainier that also helps keep you warm.