I have done lots of San Diego winter cycling. It is a pretty nice climate. You will have the exception when you take off at 7:30 am and it is around 45. That plus the fog is a pretty chilly downhill.
I have an earlier version of this jacket. It is ok normally. On the coldest of mornings you might need to have really good gloves, warm socks, and a warm underall t shirt, under your jersey. But , since it is usually 70 by noon, you need be able to fit all this stuff in your jersey pockets.
But, then maybe I am more warm blooded than most.