WESTERN WILDFIRES

Climate Central's analysis of U.S. Forest Service records shows that the average annual number of large wildfires in the western U.S. more than tripled between the 1970s and 2010s, with the area burned increasing more than six-fold. The report attributes these trends to rising temperatures, decreased snowpack, and earlier snowmelt. Projections using the Keetch-Byram Drought Index (KBDI) suggest that high-risk fire days will increase substantially by 2050, particularly in Southwestern states. The report also highlights the growing risk to populations living in the wildland-urban interface (WUI) and the health impacts of wildfire smoke.

• Between the 1970s and the 2010s, the average annual number of large fires (those exceeding 1,000 acres) in the western U.S. more than tripled, while the area burned by these fires increased by more than six times.
• The wildfire season in the western U.S. has lengthened by approximately 105 days since 1970, shifting from a typical duration of under five months to more than eight months.
• In Alaska, the annual average number of large wildfires increased sharply in the 1990s, with the last 25 years seeing twice as many fires as the previous 40 years. The state's wildfire season is now 40% longer than in the 1950s, an increase of 35 days.
• Climate projections using the Keetch-Byram Drought Index (KBDI) indicate that the number of high-risk fire days (KBDI above 600) will increase by 46% between 2000 and 2050 across 10 western states under a high-emissions scenario. Arizona is projected to have the largest increase, with 34 additional high-risk days per year.
• Rising temperatures and changing precipitation patterns are key drivers of wildfire risk; summer temperatures in the West increased 2.1°F over the last 45 years, and an increasing percentage of winter precipitation is falling as rain rather than snow.
• Wildfire costs and risks are increasing as populations grow in the wildland-urban interface (WUI). California has the largest population living in the WUI (11.3 million), while Wyoming has the highest percentage of its population in these areas (82%).

APA

Kenward, A., Sanford, T., & Bronzan, J. (2016). WESTERN WILDFIRES. Climate Central. http://assets.climatecentral.org/pdfs/westernwildfires2016vfinal.pdf

Chicago

Kenward, Alyson, Todd Sanford, and James Bronzan. WESTERN WILDFIRES. Climate Central, 2016. http://assets.climatecentral.org/pdfs/westernwildfires2016vfinal.pdf.

Wikipedia

{{cite report |last1=Kenward |first1=Alyson |last2=Sanford |first2=Todd |last3=Bronzan |first3=James |title=WESTERN WILDFIRES |publisher=Climate Central |date=June 2016 |url=http://assets.climatecentral.org/pdfs/westernwildfires2016vfinal.pdf |access-date=23 October 2026 |via=Climate Insights Directory}}

BibTeX

@techreport{kenward2016western, author = {Kenward, Alyson and Sanford, Todd and Bronzan, James}, title = {{WESTERN WILDFIRES}}, institution = {Climate Central}, year = {2016}, month = jun, url = {http://assets.climatecentral.org/pdfs/westernwildfires2016vfinal.pdf}, urldate = {2026-10-23}, note = {Indexed by Climate Insights Directory} }