UCLA

In the summer of 2015, Eastern Washington experienced over 2000 fires that burned in excess of 450,000 ha, took the lives of three firefighters, and caused hazardous air quality throughout much of the region. In Eastern Washington, summer 2015 was nearly 1�C warmer than the previous record warm year and 1.4�C warmer than climatology. Dead Fuel Moisture (DFM) in summer 2015 was near the extreme low of record. We examine both Washington’s 2015 fire season and the 32-year fire record with respect to temperature and precipitation climatology and other potential drivers of fire. We find that the extreme 2015 fire year was not attributable to any one physical factor, but rather to a combination of anomalously dry and warm summer conditions, a lightning storm in mid-August, and possibly the encroachment of invasive cheatgrass. These risk factors combined to drive large fires that propagated quickly, mostly through grasslands and into forested areas.