Hi - Good question and a hard one to answer! This is a coastal environment, so you'll hear it's foggy a lot. We do have fog, but more often it's high clouds, sometimes with light precipitation. We also have amazingly spectacular days where the colors are jewel-like and we can't believe what a paradise we live in. We get a lot of foggy/cloudy days in the summer - June, July, August - and I think these times feel especially cold and gloomy because most of us expect sun in the summer. Many days the fog and clouds burn off and we have gorgeous afternoons even after those yucky drippy mornings. And lots of people just drive over the hill to get their sun fix. The Fall is the best (sunniest, warmest) time, but I also love Winter and Spring. We have so many lovely days - especially right after a rain. I just doesn't get any better.
On those super hot days when everyone east of us is sweltering, we are loving the marine layer. And when other areas freeze, we generally don't because of the marine layer - the weather is much more moderate here.
If you're considering the coast, I'd suggest visiting a few times, at different times of day, and look at different areas. The "Banana Belt" of lower El Granada might be sunny while Half Moon Bay is not. Also talk to the locals! You'll get an honest answer based on each person's experience.