My hands are the LAST things that I cover up so was answering under the assumption that the paddler already had on many fleece layers, wool socks and other warm stuff on his feet, and a good head covering. 

You lose sooooooooooo much heat through your head and core.

When it's 20 degrees outside, I dress in enough layers to make sure that my chest is almost sweating BEFORE I put on.  I wear pogies and gloves to start.  Within 15 minutes I can usually take off either the pogies or gloves.

Scott
DragoRossi
www.100waves.com
www.ARTandWATER.com