Like a lot of folks, if I didn't ride in the rain, I wouldn't get much riding in. I ride everyday I can; usually 5 days a week. I rode the whole week that we had temps in the low teens. My wife commutes to work a couple of days a week year round (her non-swim days). Fenders, good rain gear, helmet cover, and shoe covers or "winter" shoes make riding in the rain fun! I believe that it is usually a lot harder on the bike than it is on me.
"There is no such things as bad weather, just inappropriate clothes" However, while skiing today I was beginning to question that statement.