squeakr

It kind of depends on the day of the week. Weekend or weekday. Weekends are likely to be busier if it's a nice day, less busy if it's been cloudy.

I say it's hard to predict because we just went down to half Moon Bay this past Saturday. It was a gorgeous day and we assumed we'd hit traffic as we left rather late – we left San Francisco around noon time. However there was no traffic either way and even coming back around 7 PM, when the beaches we're starting to thin out was not a problem.

That may have been just an odd day or there's a window where there's less traffic. I would certainly leave a couple of hours and as I am very paranoid about driving times more like three.