How Much Rain Does California Need To Get Out of Drought?

The torrential rainfall across much of central and northern California may have helped to pull a tiny piece of the state out of drought.

Data from the U.S. Drought Monitor shows that while 97.93 percent of California is experiencing some degree of drought, the remaining 2.07 percent is only classified as "abnormally dry." These small slivers of drought-free land are in the northern county of Del Norte on the Oregon border, and in the south, spanning Imperial County and a tiny section of Riverside County.

As recently as October 4, 2022, only 0.23 percent of the state was drought-free. Additionally, "exceptional drought" is now not seen at all in California, despite 7 percent of the state being in this category on December 27.

These changes away from the arid drought-ridden conditions throughout the state may be a result of the deluge of rainfall seen since the start of 2023, caused by several atmospheric rivers being flung from a bomb cyclone in the Pacific Ocean.

However, a lot more rain would be needed to drag California out of its decades-long megadrought, as short-term fluctuations in how dry an area is at a given time is drastically different to the long-term trend of dryness across the state.

Want to know why heavy rainfall isn't enough to solve California's drought crisis? Check out Newsweek's in-depth explainer

On December 31, 5.46 inches of rain fell in a single day in San Francisco, making it the second wettest day in the city in the past 170 years. Throughout the first week of January, the state has been inundated by a series of storms, bringing even more rain, flooding and high winds. December 26 to January 4 is now the record holder for the wettest 10-day stretch ever in San Francisco.

"Multiple systems over the past week have saturated soils, increased flow in rivers and streams, and truly set the stage for this to become a high-impact event," the National Weather Service said in a statement.

In the newly drought-free areas in Del Norte County, a large amount of rain fell over the past week. Fort Dick in Del Norte, which has an average of 95 wet days per year, received over 2 inches of rain on January 8. Imperial County and Riverside County have experienced no rainfall in the past few days, however.

The rain has impacted other drought-ridden areas of the state, including Lake Shasta, situated around 170 miles north of Sacramento, which is the largest reservoir in California. On December 25, 2022, Shasta's water levels were at 908.42 feet above sea level. As of January 8, Shasta's water levels had risen to 942.46 feet.

The U.S. Drought Monitor data was last updated on January 3, meaning that even more of the state may have received enough rain to change its drought status in the week since, as well as the incoming bad weather in the next few days.

Much more rain will be required to further lift California out of its drought conditions, however.

"So far the rainfall in the northern Sierra Nevada, which our largest reservoirs depend on, is at about 40 percent of the annual average," Roger Bales, a water and climate engineer at the University of California, Merced, previously told Newsweek. "We need more precipitation, closer to the average, to "refill" the reservoirs. We need 2-3 more big storms in Jan-March."

Several years of consistent rainfall would be needed to help remedy the state's drought, Lowell Stott, professor of earth sciences at the University of Southern California, told ABC7News.

"Rain in California will certainly help, but it won't alleviate the drought overall in the western U.S.," Stott said.

The wet weather may not even stick around for the rest of the winter, meaning that the progress made by these rainstorms may not have an impact on the state's drought long-term.

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