The cold Michigan winters have made Rich Thomas a Filson lover.  He is an avid fly fisherman and upland bird hunter and never takes off for an adventure without his Filson merino wool gear on. I am an avid Filson lover and I winter steelhead in Michigan where the average temp during January is 17-22 degrees. I wear a base layer of  Filson merino wool and heavy weight merino wool socks with my Simms exstream gortex waders, and then a fleece layer over this with a Gortex jacket. I fish hard all day, I always wear mernio wool till the temps are above 32, then its my Patagonia Capiline.