You could reduce the ventilation temporarily and definitely dry out your coop. I have a pool in a fully-enclosed metal carport that I heat with a wood stove. Without it's drying heat water will be dripping off the ceiling; with it it's bone dry.
A small wood stove would probably dry out a coop faster than anything. After reading this thread I may incorporate the ability to use one into my next coop.
A really easy way to convert C to F is to type -43 C F temp into Google (others might work, don't know) and it will display the conversion.
example > https://www.google.com/search?sclient=psy-ab&site=&source=hp&btnG=Search&q=-43+c+f+temp&oq=&gs_l=&pbx=1