I think its important to make a distinction between cold and warm rain. What city is the OP from? I started riding in cold rain in Sacramento CA. It only rains in the winter there. In Sacramento I wore a full rain jacket with pit vents, rain pants, and gaiters.
Now that I live in Seoul where the winters are dry but the summers bring in the monsoons I don't wear anything special. Its so humid in the summer here that I just wear fast dry cloths in the summer to help deal with sweat. When it rains I just get soaking wet, even on my way into work, and then change into dry clothes when it get there. If I wore a rain jacket in the summer here I would end up soaked and selling of sweat rather than just being wet.