It is also only available in a limited range of colours and retains odour readily. There are also blends of these synthetics that make the best of each beneficial characteristic. The key performance characteristics are warmth when it gets wet and quick drying. When your clothing is wet it draws your body heat away from the skin so the body will generate more heat to compensate for it. Heat conduction is a function of the moisture promoting the movement of heat along the fibers away from your body.
Heat convection is heat loss due to the movement of air around the body.
Properly designed garments with 'venting' capabilities will alleviate overheating, the most common problem paddling. Most venting occurs at the chest and neck. A good garment will allow you to tighten up all the openings if the weather really turns sour. So look for a jacket with a hood that allows some movement, and opens easily if conditions are changing rapidly. For hard paddling a breathable top is nice except if it starts to rain or the weather picks up.