You're right if you consider "Northern California" to be North of Sacramento. That's like a third of the state by landmass, and probably like 10% by population.
A Southern Californian might lump the SF Bay Area and Sacramento into "Northern California," or more likely "NorCal," but generally people from the Bay or central coast wouldn't consider themselves to be in "Northern California" as opposed to southern the same way southerners would.
You're right if you consider "Northern California" to be North of Sacramento. That's like a third of the state by landmass, and probably like 10% by population.
A Southern Californian might lump the SF Bay Area and Sacramento into "Northern California," or more likely "NorCal," but generally people from the Bay or central coast wouldn't consider themselves to be in "Northern California" as opposed to southern the same way southerners would.