Get a tube of this Nikwax product on Amazon.com: https://amzn.to/2N5DTGE
If you need waterproofing for you boots, what do you turn to? There a literal ton of products on the market. Only a few are really effective. One of them is the Nixwax waterproofing. Aaron used it in Greenland on his tundra expedition during the beginning of the Arctic winter. Aaron reviews this product. He provides the good points and potential drawbacks.
Nixwax leather waterproofing on Amazon.com: https://amzn.to/2N5DTGE