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Large California wildfires: 2020 fires in historical context

August 21, 2021


California in the year 2020 experienced a record breaking number of large fires. Here, we place this and other recent years in a historical context by examining records of large fire events in the state back to 1860. Since drought is commonly associated with large fire events, we investigated the relationship of large fire events to droughts over this 160 years period.


This study shows that extreme fire events such as seen in 2020 are not unknown historically, and what stands out as distinctly new is the increased number of large fires (defined here as > 10,000 ha) in the last couple years, most prominently in 2020. Nevertheless, there have been other periods with even greater numbers of large fires, e.g., 1929 had the second greatest number of large fires. In fact, the 1920’s decade stands out as one with many large fires.


In the last decade, there have been several years with exceptionally large fires. Earlier records show fires of similar size in the nineteenth and early twentieth century. Lengthy droughts, as measured by the Palmer Drought Severity Index (PDSI), were associated with the peaks in large fires in both the 1920s and the early twenty-first century.

Publication Year 2021
Title Large California wildfires: 2020 fires in historical context
DOI 10.1186/s42408-021-00110-7
Authors Jon Keeley, Alexandra D. Syphard
Publication Type Article
Publication Subtype Journal Article
Series Title Fire Ecology
Index ID 70224577
Record Source USGS Publications Warehouse
USGS Organization Western Ecological Research Center