Clothing:
The weather in Patagonia is constantly changing. One afternoon it may be 70° (+) and sunny, down right hot;  then only a few hours later it may be rainy, damp, windy and in the low 50°s or cooler. It is not uncommon to have morning temperatures in the mid to low forties, especially when clear weather prevails, warming to a balmy 60° or 70° degrees by the middle of the day. Clothing strategies should be based on the "layering system." Here a formula that will work well for you.

1. Base Layer:
Start off with a (synthetic) type fabric next to your skin. This often is a pair of thermal underwear (tops and bottoms) and they usually come in three weights: light, mid and expedition.  According to your individual metabolism, pick what is best for you. Synthetic (non-cotton) materials retain little moisture and "wick" moisture away from your skin. This is very important when you are walking in waders or when outside temperatures heat up.

2. Thermal Layer:
Your second layer of insulation should match the weather and conditions you are going to be fishing in, lightweight insulation for cool weather, mid-weight for colder conditions, and heavy weight for really frigid conditions.  Fleece is an outstanding choice here in either tops and bottoms or overalls.  Wool is also a good choice, as it stays warm when damp, but dries very slowly.

3. Outer Shell:
(Rain jacket & Waders):  Your final layer should be a rain jacket and waders