I live in So. Cal, so it doesn't get as cold as many parts of the country. But it does get nippy. Today it was 38 at the start of my club ride. My usual cold weather gear is a regular weight jersey (as opposed to summer weight), arm warmers, vest and leggings (or tights or whatever you want to call them). I don't like leg warmers, because no matter how much I ride my bike, the back of my thighs are still squishy enough to squeeze out of the leg warmers. So there's always a squishy lump under my shorts where my leg warmers end. I, therefore, wear full leggings over my cycling shorts. I can get cycling leggings with padding, but I can usually reuse the leggings without washing them every time and don't want to buy multiple pairs of cycling pants in addition to my cycling shorts. I also prefer the flexibility of taking off the leggings if I get hot, though I rarely take them off. I kind of know now at what temp I need the leggings and, if it does get a little warm, I can take off my vest and arm warmers and typically I'm not too hot from leaving on the pants. My friend does the same.

I don't know the lowest temp my "cold weather uniform" can work for, but apparently it works fine in the 30's.