How Severe has the California Drought been?

Assessment Report: Causes and Predictability of the 2011-2014 Drought by NOAA Drought Task Force, Seglar, et al, 2014

California statewide precipitation during the last three winters (November-April 2011/2012 through 2013/2014) ranked the second lowest since official measurements began in 1895. Only the consecutive three-year period of 1974/1975 through 1976/1977 was drier. As one critical indication of the cumulative and growing impact of this drought, the September 2014 assessment of statewide water storage was only about 50% of average for this time of year, according to the California Department of Water Resources. Water supply depletion has not resulted from the lack of precipitation alone, but also from very high temperatures with the 2013/2014 winter being the state’s warmest on record.

As the new 2014/2015 wet season commences, the current state of drought as assessed by the US Drought Monitor indicates almost all of California to be experiencing extreme to exceptional drought severity. The situation deteriorated greatly during the past year – the third consecutive year of low precipitation and the driest of the three. Exceptional drought conditions cover over half of the state as of December 4, 2014, whereas one year earlier no regions in the state were considered to be under exceptional drought conditions.

The Summary of the report and full report can be accessed here.