OK, so it's been a while since I was a full-time commuter, but if memory serves there is nothing on the Lord's Green Earth gonna' keep you dry. Let "dry enough" be your goal. What you're aiming for is to be able to repel enough water so that you're not faced with hypothermia which is the real weather issue. . .wetness is aesthetic not life and health critical [unlike hypothermia]. [Tangent: It's SO nice to have a place to clean up and get dry when you get to work. . .Mmmmmm. In a former life I commuted to a hospital laboratory service and had access to the showers our pathologists used after autopsies. . .never heard a peep from the customers.]

Here're some points:

1. It's only wetness,
2. You're already wet on the inside, and
3. Any raiment that will block all water coming in will also soak you in sweat.