Very true what some of the others have said. Try to keep your feet dry which means when hiking in try to do it on the cold side until you get your spot, then put on your hat and outer layer to keep yourself from sweating. Also, no matter how thick the boot make sure it has extra room with thick socks, either poly or wool socks that is. I duck hunt in the teens in 600 gram boots in wet waders and my feet aren't cold. Another old rule- if your hands and feet are cold put on a warmer hat. One last thought- NO COTTON!