Both my son & daughter have this shoe and it seems to be quite waterproof from my experience. The only thing better would be a GoreTex treated boot. I bought rain gators for them and they wore their Keens with the gators to play in the snow and when we got home, their feet were still dry. With out rain gators you may get some wetness around the ankle or at the tongue of the shoe where there is fabric. As far as the size, you need to order a size up...they run small. For example, my daughter wears a size 1-1.5 but wears a size 2 in Keens. My kids are hooked on Keens & say they are the most comfortable shoe ever. They are such a well made shoe that they always outgrow them before they ever wear them out. I usually end up passing them onto another child we know or selling them on craigslist because they are always in such good condition when they outgrow them.