I've found that my motivation to ride has kept me out on days when I might not otherwise ride. (Before you say it, I'm not in Phoenix. We have winter here in northern AZ, though it's been mild this year to say the least.) I've done more rides in cold weather and have found that above 20F I'm good. Above 30 and I'll take some wind and clouds. Wet and cold, well, that's another issue with the dirt road up to my place, but I've done it before on a bike that's no longer in the stable. you just have to get used to it mentally. Your body can do it already.