Welcome to hunting in the NW in the fall! You only have 2 real options, the first, do as Brian said and keep them stored one layer down, the second, carry a soft cloth in your pocket to wipe the lenses off. I keep my rubber eye pieces rolled down, which doesn't really help keep them dry but it does help with keeping the lenses from fogging and makes it easier when wiping the water off. Keeping your fletchings dry and your broadheads from rusting is another challenge! Good luck with your hunt and stay dry!