Our winters are rainy but not very cold. And the rain we get is pretty gentle compared to the east and midwest. So I usually ride when it's rainy.

The big exception is that I sit out the first rain of the season. All that oil in the asphalt floats up, making it pretty treacherous. Worse, though, is that the drivers turn into complete idiots in the first rain. This may be a California thing, I don't know.