August is usually considered the best Month to
head South. The Pacific High is usually pretty well set by then.
The Northbound trip is harder to pinpoint. We just
came up last month and had following Seas for a couple of days after a pretty good day of bashing coming out of
San Francisco.
I think May-June has a better chance of a following seas Northbound, but you may have to wait a while to get a good window.
Good Luck