How Much Rain Is Needed to End the California Drought? 

How Much Rain Do We Need to End the California Drought? 


First, drought, like beauty, is in the eye of the beholder. Each different user group has their own metric for how much is enough for them to breathe easier.  For some activities just a normal rainfall year in their local area might be enough, while much of the state needs at least 150% of normal and some users may need on the order of 200% of normal.  Of course all of these solutions are complicated by California’s complex water delivery system which means that where the rainfall is measured is not necessarily where it is used! [The Drought Monitor and Drought Termination and Amelioration pages give some insight, though both are biased by factors related to agricultural drought.]

A simplistic way to look at the water shortage in California is to look at the rainfall deficits around the state from the past four seasons, and then add in the current rainfall season. In doing so (see table below) the deficits range from almost two times normal to about three-and a half time normal.

Or to look at it another way, all but Salinas would need an all-time record rainfall year to erase the 5-year deficit.

Jan Null, CCM
Golden Gate Weather Services