Scientific Investigations Report 20065139

Atlas of Climatic Controls of Wildfire in the Western United States

U.S. Geological Survey Scientific Investigations Report 2006-5139

By S.W. Hostetler, P.J. Bartlein, J.O. Holman

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Wildfire behavior depends on several factors including ecologic characteristics, near-term and antecedent climatic conditions,fuel availability and moisture level, weather, and sources of ignition (lightning or human). The variability and interplay of these factors over many spatial and temporal scales present an ongoing challenge to our ability to forecast a given wildfire season. Here we focus on one aspect of wildfire in the western US through a retrospective analysis of wildfire (starts and area burned) and climate over monthly time scales. We consider prefire conditions up to a year preceding fire outbreaks. For our analysis, we used daily and monthly wildfire records and a combination of observed and model-simulated atmospheric and surface climate data. The focus of this report is on monthly wildfire and climate for the period 1980-2000. Although a longer fire record is desirable, the 21-year record is the longest currently available and it is sufficient for the purpose of a first-order regional analysis. We present the main results in the form of a wildfire-climate atlas for 8 subregions of the West that can be used by resource managers to assess current wildfire conditions relative to high, normal, and low fire years in the historical record. Our results clearly demonstrate the link between wildfire conditions and a small set of climatic variables, and our methodology is a framework for providing near-real-time assessments of current wildfire conditions in the West.

Table of Contents



Wildfire and climate in the West

Seasonal cycle of wildfire.

Seasonal cycle of climate variables

Association of wildfire and climate


Fire and Climate Data Sets

Fire data

Climate Research Unit (CRU) climate data

Regional climate model data.

Standardizing climate and fire data

Study subregions

Description of subregion graphics

Fire/climate rankings and correlations

Wildfire and climate maps



References Cited

The Pacific Coast Region

The Interior Northwest Region

The Northern Rocky Mountain Region

The Central Rocky Mountain Region

The Southern Rocky Mountain Region.

The Great Basin Region

The Southwest Region

The Sierra Nevada Region

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