I'm with George here. We need the rain more than we need the warm weather. What makes California "California" regarding the many of the great plants we can grow here, and the agriculture that's unique to the US (all the good citrus, avocados, fresh veggies, almonds, etc.) relies on water, and while most of us don't get enough from the sky, we do get the "leftovers" from snow melt in the Sierra (primarily--some areas do get water from the Colorado River, but everyone knows that's precarious as well). Guess what? The Sierra is at 27% of normal for this time of year, as of today: https://cdec.water.ca.gov/cgi-progs/snow/DLYSWEQ
While I'm enjoying this ridge and the large amount of days this December with highs in the 70s, I'd trade any of these days for a good rainy day, even if the high is only 59. Until we get a few good rains, then every time we have a Santa Ana Wind in California, there will be a risk of a large rapidly growing wildfire. The reason our wildfire risk usually peaks in October is because after that there's usually enough rainfall to lesson the risk, even though the frequency of Santa Ana Winds actually increases as we go towards winter.
Unfortunately, with less ice/more water in the Arctic, there are studies showing this is related to more ridging along the West Coast and a greater likelihood of drought. (Here's one short article in case you're interested: http://www.sciencemag.org/news/2017/12/vanishing-arctic-ice-could-drive-future-california-droughts ) This appears to be the new normal. We're definitely going to have to conserve, though at least on an individual level (and also to an extent the agriculture industry), people are doing well--hence Jerry Brown's comment "Brown is the new green" (no pun intended with his last name, ha ha!) but people are letting their grass go brown when there's no rain, and at least in my neighborhood, probably 75% of yards that have grass are brown, and people just water other plants (if even that). I've slowed down my gardening myself--fewer veggies, and I haven't planted any new ornamental plants in quite a few years (fortunately, occasional fog dripping helps my jungle in front, and I give some, but not much, supplemental watering). Fortunately, I have no intentional grass (just some "volunteers") which is normally a water-hog.
Keep in mind too that the warmer the climate, the more water that is required for plants (a notable way of saying this is that in a temperate climate, 30-40 inches of rain per year makes things reasonably green, but in the tropics, that same rainfall would be associated with a mostly dry landscape). Also, keep in mind that Hayward, among other near-coastal California locations, will be able to grow spectacular plants due to the tempered seasons, regardless of if average temperatures go up or down a few degrees, but water is indeed a big limiting factor. Despite the average temps definitely being higher the last few years, the decreased rainfall and necessary conserving of water definitely has resulted in a decrease in the number of beautiful plants in people's yards here (even if it means certain tropical plants that are borderline for our climate do a little bit better).
Last bit of data, if you're curious, I've had 0.15" (not including some fortuitous fog dripping) since Oct. 1, and San Diego Airport has had 0.09" (which is the second driest Oct-Nov-Dec in history).
Anyway, that's my rant! All for now!