Where does Northern California end and Southern California begin?

As a Californian, I sometimes get questions from my non-Californian friends asking what exactly we mean by NorCal and SoCal. Everyone generally agrees that San Francisco is NorCal and LA is SoCal, but where's the border between them? Turns out, there's no one border that everyone agrees on. Below are three of my takes on potential arrangements for the border region, from most general to most specific. The maps are based on the following assumptions:

1. Everything north of San Francisco is definitely NorCal
2. Everything south of Santa Barbara is definitely SoCal
3. If it's cold and wet, it's NorCal
4. If it's a hot desert, it's SoCal
5. Neither side claims Fresno (Sorry, Fresno)

Full disclosure: I've lived most of my life in Sacramento (NorCal) and spent several years living in San Luis Obispo (which declares itself part of the Central Coast).