Statewide precipitation decrease trends
Changing weather patterns due to climate change are at least partly responsible for the dramatic precipitation decrease during the two back-to-back winters in California—the winters of 2012-2013 and 2013-2014—that contributed to the severity of the California drought.
Researchers have linked climate change to the circulation patterns that produced the unprecedented high-pressure weather pattern known as the “ridiculously resilient ridge” that blocked storms from the state.
Regional precipitation decrease trends
A study looking at data from 1979 to 2014 finds up to a 25 percent decrease in precipitation in the US Southwest related to an increase in high pressure, anticyclonic conditions during this time in the North East Pacific.