I usually check the weather radar just before leaving and dress accordingly. My commute only takes me 30 minutes or so and if it looks like I'm going to get nailed I wear a pair of cheap rain pants and a Showers Pass waterproof jacket (as mentioned in an earlier post). On occasion, I have packed rain gear and used a washroom at a coffee shop to do a quick change on the fly. I let my chain air dry but make sure I use a good lube that doesn't leach out and check it when I get home at the end of the day.