x2 on the cable. If you're using steel cable (as opposed to synthetic), remove the cable, coil it up and soak it in a bucket of oil (transmission fluid works, so does hydraulic fluid). Then re-install the cable on to the winch. If you're using synthetic rope, make sure its not winded up too tightly or else it will flatten out instead of being round.
Often, its the solenoids that are affected most by the weather, so if you can, mount the solenoids somewhere where they'll be dry (inside the cab is probably the best idea).