Weathers only part of it, a large part is cost of living and especially housing costs. People have this idea that people become mentally unwell drug addicts then lose housing then move to California for the better weather/ more compassionate state. In reality a lot of it is the reverse, people live in California, lose they’re housing due to astronomical rents, then they become mentally unwell drug addicts due to the pain and trauma they suffer on the streets.
Last point still stands though, we do need a green new deal to give these people housing and employ them in meaningful jobs to help the green transition.