If you ever snowshoe, backpack in the snow, or climb to mountain peaks that are covered in snow, you’ll want to treat the leather on your mountaineering boots to make sure that your feet stay nice and dry.
All good mountaineering boots will have a Gore-Tex or other waterproof lining that will keep your feet dry, however, that doesn’t prevent the leather on your boots from getting saturated and weighing you down.
I highly recommend using a waterproofing product like Tectron Sno-Seal on the outside of your boots, before you head to the snow. It may darken the leather a bit, but snow and water will bead up on the outside of the boot and keep it away from the Gore-Tex liner.
Check out this other article to see how easy it is to waterproof your boots.