I usually wear my bike shorts with a pair of windpants (from Target) over them (of course, the ankle strap goes on with those!). Being considerably further north than I (though not like all the NW's and Canadians!), you may want to consider tights if you can find a pair that fits well, and wear the windpants over them...

I've ridden like this in December / January & February...(but then again - I'm in North Carolina!)