A desert is defined as having sandy or rocky soil with little or no vegetation. Water lost to evaporation and transpiration in a desert exceeds the amount of precipitation; most deserts average less than 9.75 inches of precipitation per year.
Los Angeles averages about 15 inches of rainfall per year. Lima, Peru averages .2, Madrid slightly more than LA at 17 inches, Palermo in Sicily about 24.
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Very little of California isn’t desert.
Most of the coastal hills are nothing but sand.
By your definition, most of the Mojave isn’t dessert because there is lots of vegitation.
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“Los Angeles averages about 15 inches of rainfall per year.”
Yes, as I said, southern California is semi-arid (>9 but <20 inches of rain a year).