California is in a weird place due to the weather, which almost guarantees the self dumping of people living outdoors. I'd be curious to see how this factors into these equations. Much of Europe gets pretty cold in winter.
https://en.wikipedia.org/wiki/100th_meridian_west
> In the United States, this meridian roughly marks the boundary between the semi-arid climate in the west and the humid continental and humid subtropical climates in the east and is used as shorthand to refer to that arid-humid boundary.