In the summer I love riding in the rain. Many days I hope/pray/yell for a rain shower in the afternoon when going home. In the fall/winter/spring, I have ridden in wet conditions down into the upper 40's. Much below that, or if it's really pouring, I'll take the car. Any gear that would keep the water out would have me soaked inside from sweat after a 15 mile commute, so I don't really bother with any of that. And being wet in the low 40's and 30's for 80 minutes does NOT sound fun at all. So in those conditions I will drive.
Unfortunately it's looking like tomorrow is the first day since winter/spring last year that I will have to use that option. I rode a couple of weeks ago when it was drizzling and wet and 47 degrees, and it wasn't bad at all. But tomorrow is supposed to be about 39 with rain in the afternoon. No thank you.