No motorcycle jacket is totally waterproof. Water can come in at the neck, under the hem line, up the sleeves and through the zips, but some jackets do a better job of trying to keep you dry than others. First thing; forget leather. Leather absorbs water like a sponge, so you need a textile jacket. Some jackets have a waterproof coating, but what you really need is a waterproof membrane. If the waterproof membrane is removable, it will be slightly less waterproof than a jacket that has a ‘seam-sealed’ membrane. Some jackets have waterproof zips, and these add to the jacket's waterproof qualities. Air vents are a slight weak point for water ingress, but are necessary if you ride in the summer. The most waterproof jackets are constructed with what is known as a three layer laminate. This manufacturing technique prevents the rain from passing through the outer fabric. This is very effective, but makes for a jacket that is often not particularly comfortable to wear. In our view, only if you are commuting 50 miles or more each way, every day of the year, do you really need a laminated jacket. Or, of course, if you work as a courier.