If you’re staying in Santa Rosa then that is about an hour and twenty minutes north from Oakland with no traffic.
Monterey is south from Oakland about a 2 hrs depending on traffic.
Diving north of the Golden Gate can be very nice or it can be horrendous.
The weather and ocean conditions change so rapidly from day to day.
We can get glass flat conditions in winter in between the storms with great visibility, or it can be 20’ swells.
From Santa Rosa you could be at a popular dive spot in about one and a half hours. All diving in Sonoma County is north of Jenner where the Russian River spills into the ocean.
The water will be about 50 degrees average that time of year. Air temps at the coast will be 50’s to 60’s.
For dive shops up here we have
Seals Water Sports in Santa Rosa
(707) 542-3100
And in Rohnert Park there is
Sonoma Coast Divers (707) 586-0272.
It would also be a good idea to buddy up with a local to show you the ropes. If I happen to be free I’d be glad to take you for a local dive. Just PM me here when things get closer.
The diving infrastucture is pretty primitive here since people come here to go wine tasting and enjoy the scenery, not really to dive.
The diving here seems to be a locals thing.
It’s pretty much DIY with no coastal services, but there are the two dive shops I mentioned which both rent all the gear needed.
Other than that there is Monterey to the south, about 3 1/2 hours south of Santa Rosa.
They have dive boats and the works.
I don't know how many will be running since that’s the time if year they like to haul out and do maintenance.
As far as diving in San Francisco Bay? No way, nada, solid muck, no vis, too many boats, polluted as hell, too dangerous, not something anybody does. Unless maybe the sheriffs dept is looking for a body, other than that no.