List of California floods

A 2022 study found that Climate change in California will increase the extremity of water cycle events such as droughts and megafloods, greatly increasing the severity of future floods due to atmospheric rivers.

[2] In part this is due to the expectation that the Sierra Nevada mountains, which typically retain water as snow, will no longer be as cold, reducing snowpack in favor or more runoff.

[3] Every county in California has experienced a flood, which is mostly likely to be caused by an atmospheric river, which is a narrow corridor of moisture in the air that travels a long distance to produce heavy rainfall.

[4] The state of California spends more than US$2.8 billion annually on maintaining or building flood control projects.

[6][7] Prior to European settlement, these early floods predominantly affected the indigenous peoples of California.

Remains of the St. Francis Dam in March 1928
The remains of the St. Francis Dam and reservoir floor, which killed more than 400 people after it failed in March 1928
The Los Angeles River overflowing its banks near Griffith Park, in 1938
The United States Geological Survey maintains a camera on top of Humboldt Creamery in Fernbridge, California which shows the Eel River in flood stage on February 8, 2017. The flood was significantly smaller than the floods of 1955. and 1964.
The South Yuba River at Highway 49 floods after heavy rain on January 9, 2017. The flow is about 25,000 cubic feet per second (710 m 3 /s), more than 40 times the normal rate.