The difference is that what people think of as LA includes a huge number of suburbs that push out quite far east into the desert. So if you are in Santa Monica or Malibu, the climate is very comparable to coastal San Diego. If you drive out on the 10 for a ways, its going to get brutally hot and arid quite fast.
Water-wise, San Diego also gets a lot of its water from the Colorado river, but it has a desalination plant as well. I'm not sure how much impact that has on the water situation there.
Water-wise, San Diego also gets a lot of its water from the Colorado river, but it has a desalination plant as well. I'm not sure how much impact that has on the water situation there.