Between here and Hawaii, there is a whole lot of water. Between Hawaii and Australia, there is a whole lot more. Everywhere to the west and southwest of California, there is a lot of water. Unfortunately, none of this huge volume of water is useful for gardening. It is saline. It would kill plants.
Of course this is not just any water. It is the Pacific Ocean. Although the water within it is useless directly, it is what feeds the weather that provides the precipitation that becomes the water that makes gardening and everything else possible. Rain fills local aquifers. Snow in the Sierra Nevada fills reservoirs as it melts.
The weather that the Pacific Ocean feeds gets shared over a very large area. Weather that does not make rain here might make rain or snow in Nevada, or Oklahoma, or really anywhere the weather wants to go to. In fact all the oceans all over the world cooperate to make climate and weather what it is.
What is so special about the Pacific Ocean being right here off the coast is that it moderates our climate and weather. Places like Nevada and Oklahoma that are not on the coast get water from the Pacific Ocean because weather is mobilized. The moderating effect of all that saline water is not. It stays right here in coastal regions.
Water has a high specific heat. That means that it takes a lot of energy to change the temperature of water. Saline water has an even higher specific heat. The temperature of the Pacific Ocean therefore changes very slowly and very minimally.
This inhibits extremes of temperature in the air above all that saline water. Small batches of extremely cold weather tends to collect a bit of heat energy as they pass over the Pacific Ocean. Weather coming in over so much saline water can not get extremely hot without the water absorbing at least some of all that heat energy. Therefore, coastal weather is rarely extremely cold or extremely hot. Temperatures can be more pronounced a few miles inland from the Pacific Ocean, especially when the weather comes from inland. Farther inland cold and heat can get significantly more extreme.
A lack of cold weather in winter limits what can be grown here. Plants that require a good chill are not satisfied with our pathetic winters. That is why some bulbs that do well as perennials farther inland bloom only once here, and why some varieties of apple that perform well in central Washington are not grown here.
However, a lack of hard frost allows us to grow many plants that can not be grown where winters are more severe. Even if bougainvillea gets frosted every few years or so, it typically recovers. Avocados and lemons are likewise quite happy here. The weather may seem to be boring, but it certainly has its advantages.