Chart of Precipitation and Temperature from 1950 to 2020
Droughts in California Fact Sheet
Apr 14, 2021 at 11:05am
California is prone to droughts.
California has the nation’s most variable climate, and droughts are a recurring feature. Very wet and very dry years are both common, while “normal” years—widely used to describe average precipitation—are rare. Yet one dry year does not constitute a drought. Water stored in the state’s reservoirs and groundwater basins protect against individual dry years. Droughts occur when two or more successive years are very dry, and reservoirs and groundwater reserves are depleted. Significant recent droughts occurred in 1976‒77, 1987‒92, 2007‒09, and 2012‒16.
Climate change is making droughts more intense.
The past two decades have been exceptionally warm and dry, and included the hottest drought (2012‒16) in the state’s recorded history. Warming is making droughts more intense. A “thirstier” atmosphere—a direct consequence of warming—increases evaporation, which reduces water availability for ecosystems and human uses. Warming is also decreasing the proportion of precipitation that falls as snow. Snowpack is an important part of the state’s water storage system, accounting for about 30% of water supply. “Snow droughts” make it harder to manage reservoirs for water supply and hydropower generation.