Dressing For Cold, Freestone Jacket, XCR Guide Jacket

Fall & Winter steelhead weather can mean rain and lots of it. 
The word "rain" turns most people off, because they associated it with discomfort. However, rainy days don't have to be uncomfortable, 
if you dress properly.

If you dress correctly, you can be comfortable, even during long days in cold, wet weather. If you don't dress correctly, you can get cold & wet.  
As you lose thermal energy, your motor skills will suffer.  
Warm muscles perform better than cold ones. 

Many people think that preparing for rain only means the addition of a rain coat and chest high waders. 
The selection of these items is very important, but what you wear under this outer layer is also very important. 
When dressing for cold or wet weather fishing; dress from the inside out.

The layer of clothing next to your skin is the one you will feel. 
It should be soft and pleasantly warm. 
To be warm and comfortable, your skin must stay dry. This means that you not only have to keep the rain out, but your clothing also has to have the ability to disperse your own perspiration. 
Perspiration becomes a real factor after about four hours spent inside non-breathable waders.
For this reason non-breathable waders have all but disappeared from the steelhead fly fishing scene.

Your inner layer should be synthetic material for maximum comfort. This layer must be made from materials which will pass through rather than retain moisture from perspiration. 
Nylon, acrylic and polyester do not retain as much moisture as cotton, silk or wool. 
Never wear cotton clothing under your waders.
Cotton retains moisture and has very little insulation value when damp.  It becomes a a medium for fungal infections.  The organisms that cause these infections can not live in synthetic fabrics.
Maximum perspiration zones are your arm pits, groin and feet. Pay special attention to your socks. Water runs down hill and some of your body perspiration will 

collect at your feet. This happens much less with breathable waders, but is still a factor, especially if you are hiking between pools.  There is no way for wader feet to breath inside your wading shoe.  Wader feet are still made from insulating, but non-breathable neoprene.
We like thick wool/nylon blend socks that have a knitted loop pile on the inside which gives them the capacity to retain a lot of loft, even with the squeezing pressure of your waders around them. They act as a reservoir for migrant perspiration but help keep it away from your skin.  
Of this type, Outdoor Socks by Fox River are the best we've tested. 

Layering your under-wader wear for cold weather and cold water situations makes a lot of sense.  While most synthetic fabrics are soft, some just feel better next to your skin than others. 
Velour Fleece is an inexpensive, but very efficient material for under wader garments in all kinds of weather. Velour Fleece is hydrophobic, which means that it passes perspiration through it and layers the moisture against your waders instead of against your skin. "Fleece" also retains a high degree of insulation value when damp. Dutch Harbor offers exceptional warmth for weight and exceptional value!   Extra layers of Fleece and other synthetic underwear can be added for more extreme conditions.  An angler can wear 1, 2 or even 3 layers under their waders and be able to match any weather/water condition he or she is liable to encounter.  For extreme days a WindStopper jacket or vest can be very comforting.
Here is what the Simms Company says about layering!