We get almost all of our rain in the winter, so I'm usually wearing tights and a light jacket anyway. The rain tends to go right through my jacket (Performance Century II), so sometimes I'll add arm warmers if it's below 40 degrees. The only other clothing change I make specifically for rain is wool socks and shoe covers. I have a waterproof helmet cover, but it is very much like wearing a space heater on my head, so I only use it when it's really cold (regardless of whether it rains or not).