“The west coast will see some desperately needed rainfall this week, but it could take several wet years in a row to ultimately bust the drought that has plagued California and other areas of the west. And odd trend at the end of the article shows that 2 of the past 10 Decembers following a dry October and November in San Francisco have been exceptionally wet. We’ll certainly hope for one of those wet Decembers in 2013 for both Northern and Southern California.”
This map shows the percent of average precipitation in California since January 1, 2013. There are a few isolated wet spots in the deserts (likely due to some locally heavy monsoonal thunderstorms during the summer), but the vast majority of the state has seen below 50% of normal precipitation. Much of the central coast has seen below 25% of normal precipitation. This can translate to a deficit of 10-20 inches of rainfall.