A median house in San Mateo County costs 11.3x median county income. A median house nationally costs only 3.3x median national income. So if you wish to buy a house in this area (and of course many people may prefer to rent), you should avoid moving here unless you can make those numbers work.
The reality for homebuyers is a bit worse than even those numbers indicate. Income taxes in California are very high, and most of the SF and peninsula housing stock is older and smaller than the national average. The median San Mateo County home is 1500 sq. ft; the median national home is closer to 2,500 sq. ft.
Construction, renovation, and maintenance costs are higher as well. Gas taxes are higher than the national average, sales taxes are higher, electricity costs are higher, etc. SF and peninsula municipalities have planning reviews that can add tens of thousands of dollars, plus state requirements (Title 24) and local requirements (no site development without survey, civil engineer, etc.) that add still more. Also geotechnical reviews and more expensive foundations--remember we're in earthquake country, folks.
On the other hand, we have very pleasant weather. :)
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Sources: San Mateo County's median home value is $1.13M[1]. The county's median household income is approx. $100K[2]. A house costs 11.3x income. [1] http://www.zillow.com/san-mateo-ca/home-values/ [2] http://www.mercurynews.com/2014/08/28/can-working-class-fami...
The national median home is $188K[3]. The median national household income is $56.5K[4]. A house costs 3.3x income. [3] http://www.huffingtonpost.com/2014/03/13/median-home-price-2... [4] http://www.census.gov/newsroom/press-releases/2016/cb16-158....