The relationship between fire and drought in California 1987-2012

These graphs were posted without data points highlighted here last week in part because the governor of California called for additional fire staffing due to the state’s severe drought and I was curious if a correlation existed between low than average precipitation and fire:

The Governor’s drought State of Emergency directed CAL FIRE to “hire additional seasonal firefighters to suppress wildfires and take other needed actions to protect public safety during this time of elevated fire risk.”

But does a drought, or a wet year, mean “increased fires in both urban and rural areas”? The graphs below show the number of fires (1987-2012), the total acreages (1987-2012), and statewide in precipitation in California (1895-2012). If there is a correlation between increased fires and precipitation, it does not jump right out.

As noted on those graphs, a relationship between below average precipitation and either the number or acreage of fires, does not “jump right out.”

I first highlighted the well below average precipitation years (while none of the years from 1987 to 2012 are of the magnitude of 1976/1977 or this year’s drought, these data are what there is to work with). Then I highlighted those years on the fire acreage and number of fires charts. There does not seem to be a correlation either to the contemporaneous year or the one to two years following the low precipitation year. Additionally, my memory of the years 1976 and 1977 is that they were not particularly big fire years.

Still, 2014’s drought looks to be unprecedented in California’s recorded history.[1] Additional staffing for Cal Fire and increased vigilance are prudent.

Acreage burned in CA 1987-2012 annotated

Acreage burned in CA 1987-2012


California Rainfall annotated

California Rainfall


No of Fires in California 1987-2012 annotated

Number of Fires in California 1987-2012








[1] Though, Two mega-droughts occurred in what is now California long before we started to put massive amounts of greenhouse gases into the atmosphere. One mega-drought started in 850 A.D. and ended in 1090. After a 50-year break, another mega-drought came in that lasted until 1320. That is 240 years and 180 years, respectively.



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