"SF isn't north enough to be Northern California" is a common view of people who live in Eureka, Redding, etc., but in my experience people who live in SF think of it as northern California. California basically has two big centers of population: SoCal is LA and friends, and NorCal is SF and friends. Above that are remote regions heard of in legends (either old legends about the gold rush, or newer legends about pot farming).

The Bay Area is definitely not within Central California, taken as a sociogeographic term. The Central California Coast is the coastal region between roughly Santa Barbara and Point Lobos, centered on SLO. There is also another inland definition of Central California: https://en.wikipedia.org/wiki/Central_California

I would make the comparison to "Upstate New York" [0]. I like this Wikipedia article more than the one for Northern California because it admits that "there is no clear or official boundary between Upstate New York and Downstate New York".

The same is true for Northern and Southern California. There's no official distinction. Calling the Bay Area part of Northern California places too much emphasis on the Los Angeles area. By analogy, saying that "North" begins at the Transverse Ranges is like saying that "Upstate" begins at Yonkers. Ridiculous.

[0] http://en.wikipedia.org/wiki/Upstate_New_York

Yeah, we are in NorCal for all practical purposes; actual geography be damned.

Wikipedia disagrees with you.

http://en.wikipedia.org/wiki/Northern_California

"Northern California is the northern portion of the U.S. state of California. The San Francisco Bay Area (which includes the cities of San Francisco, Oakland, and San Jose), and Sacramento (the state capital) as well as its metropolitan area are the main population centers."

Klamath Falls is in Oregon. Common joke up here is "If you're south of Hilt, you're SoCal."

I meant Klamath.

It's relative. For example, most of the people in what is called "Northern Ontario" really live in almost-southernmost Ontario. That probably drives the people who really do live in the north crazy, but since there are almost none of them, almost nobody cares.