The 2011–2017 California drought persisted from December 2011 to March 2017 and consisted of the driest period in California's recorded history, late 2011 through 2014. The drought wiped out 102 million trees from 2011 to 2016, 62 million of those during 2016 alone. The cause of the drought was attributed to a ridge of high pressure in the Pacific ocean—the "Ridiculously Resilient Ridge"—which often barred powerful winter storms from reaching the state.
By February 2017, the state's drought percentage returned to lower levels seen before the start of the drought. This change was due to an exceedingly wet pattern caused by atmospheric river-enhanced Pacific storms, which caused severe flooding.
In mid-March 2019, California was declared drought-free except for a small pocket of abnormally dry conditions in Southern California. This declaration followed a series of powerful Pacific storms during the first few months of the year, which coincided with the U.S. experiencing drought conditions in the fewest parts of the country since 2000.
Why this event still matters
Historical incidents shape the rules that protect people today — building codes, evacuation policy, warning systems and inspection regimes almost always trace back to a specific disaster. Studying 2011–2017 California drought alongside current events is how preparedness improves.
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