Rainy days like today are just part of your training.

You go out and you ride in rain like this as if you were out on a normal sunny day. That way if you are out and suddenly get rained on unexpectedly - you're all prepared. This is exactly what happened on the Amtrak Century last month. Quite a few cyclists got all sketched out. But since I had the distinct pleasure of riding through a 30 minute pop-up thunderstorm/flash flood in Maryland over the summer it was not a big deal to me a all.