Primarily because of population and job growth, the strongest predictors of real estate value...but also the weather, climate, economy, etc. 

Ordinance from the city would be good, as regulation means it is allowed legally and would make it more difficult to ban it (although I don't think that is likely to ever happen).You are probably aware of the climate -- Palm Springs (city proper), just passed an ordinance limiting the number of rentals you can have per year.

@Mark KelleyMark, the two responses are on the money, but I grew up in "MUGGY" Oklahoma City and thus even though the climate here is much more favorable I simply have to have AC to sleep.

Obviously that is speculation, and based on political climate. 

This house is on a crawl; wonder if that would work in our climate but definitely worth looking into, thanks!

Best climate on earth

(easier to be homeless in a warmer climate!)

I live in a cold climate and my tenants where I was paying the heat were setting their thermostats at 78 degrees and leaving their windows open when it was 10 degrees outside and wearing shorts and tshirts and going barefoot.

I would enforce the current lease, set a climate of being firm but fair, and maybe offer them an early out if they are not liking the direction things are going.  

After that, you're on a roller coaster ride at the mercy of market conditions, political climate, and "acts of God."