Some Californians like to pull the leg of people from the less temperate regions. I personally like to send photos of the oranges, lemons, limes, avocadoes, etc. in my backyard in the middle of winter, etc.
I am a native Californian (62 years) and while the summers are usually warm and very dry the winters are cool, not cold, but often wet.
I graduated HS in San Jose (Milpitas) and also graduate school at San Jose State. During the winter months we get about as much precipitation as the eastern or Mid-Western areas do during their rainy seasons. the difference is the ubiquitous continuous 5-7 month droughts every summer.