>...One is the climate...
71% of homeless people were living in SF just before becoming homeless. Only 10% come from outside of California (and its climate)[0]
This pretty clearly shows homeless has alot more to do with the cost of housing relative to wages jobs then good weather.
[0]pg 33 of http://sfgov.org/lhcb/sites/default/files/2015%20San%20Franc...