The Santiam Fire was a very large wildfire that burned in Marion, Jefferson, Linn, and Clackamas Counties, in northwest Oregon, United States. Having ignited in August 2020, the 402,274-acre (162,795 ha) fire ravaged multiple communities in northwestern Oregon, before it was fully contained on December 10, 2020. The fire started as three separate fires. The Beachie Creek, Lionshead, and P-515 fires were ignited by lightning on August 16, 2020. The first three fires gradually grew in size, before explosively spreading in early September during a heatwave, fanned by powerful east winds. Early on September 8, the Beachie Creek and Lionshead Fires merged, and the combined fire was labeled the Santiam Fire, before being returned to their original names a couple of days later.[7] The P-515 Fire merged into the Lionshead Fire a few days later.[8][7] The Santiam Fire destroyed over 1,500 structures, including nearly the entire cities of Detroit and Gates, with Idanha, Mill City, and Lyons suffering varying amounts of damage, becoming one of the most destructive wildfires in the recorded history of Oregon.[9][10] The fire killed five people.[4][11] On September 10–12, 2020, there were fears that the Santiam Fire would merge with the Riverside Fire to the north.[7]