I've lived outside NYC and in SoCal. I don't think fair to only consider the total numbers (especially "living outdoors") when one place is freezing and inhospitable for a few months every year while the other is relativity (and in some parts, actually) a tropical paradise. People are going to migrate from all around the country to the most comfortable places to live outside. Not to mention cities literally bussing their homeless out- NYC was actually the first and still has the largest program:

New York appears to have been the first major city to begin a relocation program for homeless people, back in 1987. After the current iteration of the program was relaunched during the tenure of mayor Michael Bloomberg, it ballooned, and its relocation scheme is now far larger than any other in the nation. The city homelessness department budgets $500,000 for it annually.