Today I rode 8 miles home from Queens to Manhattan in by far the very heaviest downpour of a long, wet day. Half a block after I started I was already soaked, but there was nothing to do but continue.
It was the wettest ride I've ever had on any two-wheeled vehicle; when I arrived, my boots were full of water. Surprisingly, my top half was mostly dry. I was wearing a Tucano Urbano light raincoat (with armor) that sealed well at the neck. But my pants were soaked through to the johnson within 30 seconds. I have rain pants, but I was cocky and thought I could get home without needing them.
I rode slower than usual and kept my brakes dry. One of the things I learned is that if you're careful, you can ride an Enfield through six-inch-deep standing water with no casualty except your dry feet.