Are Coastal Californians Energy-Smarter Than Their In-Land Counterparts?

Here is an example of an ongoing work based on PG&E public data. The charts cover the PG&E service territory. Each dot on the chart represents the centroid of a zip code. The value associated with a dot is the average monthly household consumption for the zipcode represented by the dot. This average has been calculated based on the data from 2012-01-01 through 2016-12-31.

We notice that the Bay Area predominantly consists of "low" consumption zipcodes (blue dots). The trend continues all the way down along the coast. In contrast, the middle part of the state - Redding, Chico, Sacramento, Stockton, Modesto, Merced, Fresno, Visalia, Bakersfield - predominantly consists of "high" consumption zipcodes (green dots). The far Eastern part of the state, the forests, is again predominantly "low" consumption. There are only a handful of zipcodes that show "super-high" consumption (red dots).

What could be the reasons for this pattern? Are the coastal Californians energy-smarter than their in-land counterparts? Or perhaps the size of the household has a role to play in this. Could it be that the climate in the coastal region is more conducive to consuming less energy? Also, what could be the reason behind the "low" consumption in the forest area? Feel free to chip in with your explanation or ways to get to the bottom of it.