Since the OP hasn't returned for awhile, I'll throw this out for the rest of you. I have worn this sock from the low teens to 80 degree temperatures in 16 inch un- insulated snake boots. My feet have never gotten cold or uncomfortable in either extreme. These socks wick moisture amazingly and are the single best cold weather purchase I've made. They are very thick and should add about 1 1/2 to your boot size.
http://www.basspro.com/RedHead-16-Mo...ROSSEL-PRODUCT .