Good snowboard and ski pants should protect you from the extreme weather conditions, including wind and snow; they should provide some padding in case of falls; and they should be comfortable and keep you warm. In warmer conditions, you may chose to wear snowboarding or ski pants with no additional layers underneath, but in cold weather it is advisable to wear sports pants or something similar for extra insulation against the cold. This is especially relevant when you can expect to wait in long queues for ski lifts.
The Three-Layer System
The three-layer system for outdoor ski and snowboard attire is an industry-recognized manner of maintaining a comfortable balance of warmth. As the name suggests, it consists of three layers: the base layer, the insulation layer and the third layer, or outer shell. The base layer is in close contact with your skin, serving to keep moisture away from the body, while the insulation layer keeps you warm by trapping warmth. The outer layer serves to protect you from the wind, rain and snow, but it should also be made of breathable material, allowing moisture to leave.
Snowboard pants are typically looser and roomier than ski pants and often combine two or three layers of the three-layer system. Most will have a thin insulation layer, also serving to keep moisture away from the skin, and they will also have a breathable, waterproof outer shell. Snowboarders need roomier pants largely to allow for an increased range of motion, especially when doing snowboarding tricks and jumps. Snowboarding pants are also likely to have increased padding in the knees and buttocks. If you are a beginner, make sure you look for pants that have the maximum level of protection, as you can expect to fall while learning.
Ski pants generally offer the same benefits as snowboarding pants, but you may prefer tighter-fitting ski pants, as they will retain more warmth. If you are likely to be out in very cold conditions, you may opt for a roomier version to allow you to add an extra base layer underneath. Although you should not expect to find yourself on the ground quite as much as when snowboarding, it is still advisable to have padding around the knee and buttock areas, in case of a fall. Ski pants come in several styles, including some with low waists and others with removable suspenders, useful for keeping the pants in place.
Remember that even if it is a relatively sunny day, do not participate in snow sports without wearing special outdoor ski or snow pants. Jeans or simple waterproof pants will not do. This is especially important if you are a beginner, as you can expect to spend a significant time falling down on your knees or behind.