The August Complex fire was a massive wildfire complex that burned in the Coast Range of Northern California, in Glenn, Lake, Mendocino, Tehama, Trinity, and Shasta Counties. The complex originated as 38 separate fires started by lightning strikes on August 16–17, 2020. Four of the largest fires, the Doe, Tatham, Glade, and Hull fires, had burned together by August 30. On September 9, the Doe Fire, the main fire of the August Complex, surpassed the 2018 Mendocino Complex to become both the single-largest wildfire and the largest fire complex in recorded California history. On September 10, the combined Doe Fire also merged with the Elkhorn Fire (originally a separate incident) and the Hopkins Fire, growing substantially in size. By the time it was extinguished on November 12, the August Complex fire had burned a total of 1,032,648 acres (417,898 ha), or 1,614 square miles (4,180 km2), about 1% of California's 100 million acres of land, an area larger than the state of Rhode Island.
The fire largely burned within the Mendocino National Forest, with portions spilling over to the Shasta-Trinity National Forest and Six Rivers National Forest in the north, as well as private land surrounding the forests. Large areas of the Yolla Bolly-Middle Eel Wilderness and Yuki Wilderness had also been burned. Rugged terrain combined with consistent high winds and record heat complicated firefighting efforts. Although more than 2,900 personnel were deployed to the fire through mid-September, it took almost three months to fully contain the fire. The U.S. Forest Service managed the firefighting effort, with assistance from the California Department of Forestry and Fire Protection.
Due to the immense size of the affected area, the fire was managed as four separate incidents (initially three) within a larger complex. The Doe Fire was defined as the August Complex South Zone and the Elkhorn Fire was defined as the August Complex North Zone, which was later divided into the August Complex Northwest Zone and the August Complex Northeast Zone. The August Complex West Zone was split off from the western portions of the Elkhorn Fire and the Doe Fire, and was managed by Cal Fire.
Due to the remote location of the fire, there were no civilian fatalities, while 935 structures were reported destroyed. However, firefighter Diana Jones was killed, and at least two others were seriously injured.
On the early morning of August 17, thunderstorms carried northward from the weakening Tropical Storm Fausto moved across Glenn and Mendocino Counties, starting at least 13 fires. By 5:00 pm PDT, the Doe Fire in Glenn County 35 miles (56 km) north of Willows had grown to 100 acres (40 ha), and firefighters had arrived on the scene. Most of the fires were on the Grindstone Ranger District with one on the Covelo Ranger District, ranging in size from 0.5 to 15 acres (0.20 to 6.07 ha). Thunderstorm activity continued for another couple of days, igniting even more wildfires on August 17. On the morning of August 17, the Elkhorn Fire was ignited north of the Doe Fire and east of the Hopkins Fire, near Maple Creek, in Tehama County, which was separate from the August Complex at the time. By 11:00 am PDT on August 17, five fires had been contained, while the Doe Fire had grown to 550 acres (220 ha). In addition, the Box Fire in the Snow Mountain Wilderness reached 20 acres (8.1 ha), and the Rockwell and Pine Kop Fires west of Elk Creek had burned 175 acres (71 ha) and 80 acres (32 ha) respectively. Aided by thunderstorm activity and strong winds, the fires expanded rapidly throughout the day, and more fires were discovered bringing the total to 20. Forest Service officials decided to manage these fires as one incident, the August Complex.
On the morning of August 18, the Doe Fire was estimated at 1,400 acres (570 ha), while the Rockwell and Pine Kop fires were at 800 acres (320 ha) each. The Box Fire had been mostly contained and held at 25 acres (10 ha). Over the next two days, hot dry weather and gusty winds caused the fires to explode in size. Additional fires were discovered, increasing the total to 35. By the morning of August 20, the fires had burned 65,030 acres (26,320 ha) and were advancing downslope to the east. In Glenn County, evacuation orders were issued for parts of Elk Creek, Chrome, Burrows Gap, and Red Mountain, and an evacuation warning for Grindstone Rancheria. In the afternoon, the complex had grown to 116,372 acres (47,094 ha). All of Glenn County west of County Road 306 was placed under an evacuation order. On August 21, due to continued high fire danger, the Mendocino National Forest was temporarily closed to all public access.
By August 24, two additional fires were identified, bringing the total number of new fires to 37 and overall acreage to 177,750 acres (71,930 ha). At this point, some of the larger fires had burned together. The Doe Fire absorbed the Rockwell and Pine Kop fires and was at 153,083 acres (61,950 ha). Firefighting efforts were directed largely at the Doe Fire and at the Tatham and Glade fires, which had burned 7,958 acres (3,220 ha) and 13,888 acres (5,620 ha), respectively. The Hopkins Fire, in the Yolla Bolly-Middle Eel Wilderness further north, had expanded to 2,153 acres (871 ha) and was being monitored for further growth. Ten structures were destroyed, though no deaths or injuries were reported. A total of 433 personnel were assigned to the fire. By August 27, the complex had increased in size to 200,467 acres (81,126 ha). The Doe Fire had expanded to 162,326 acres (65,691 ha) and was 31 percent contained, as firefighters successfully stopped the fire from advancing further east and were building a containment line to the west. There was little containment on the Tatham Fire, now at 8,958 acres (3,625 ha), the Glade Fire, now at 19,684 acres (7,966 ha), and the Hull Fire, which was at 4,885 acres (1,977 ha). On August 28, the complex's total area had increased in size to 212,010 acres (85,800 ha), and was 18 percent contained.
On August 29, the Doe Fire absorbed the Tatham Fire, while the Hopkins Fire had spread east into the Shasta-Trinity National Forest. The Doe Fire was now 52 percent contained, though the complex overall remained at 18 percent, as the other fires continued to spread. A heat wave combined with extremely smoky conditions hampered aircraft operations. On August 30, the Doe Fire also absorbed the Hull and Glade Fires, making the complex essentially one large fire, with the exception of the Hopkins Fire to the north. There were 607 personnel committed to the fire; crews stopped flames from advancing further south towards Lake County, but the fire continued to burn largely uncontrolled to the west. A containment line was being constructed west of the Glade Fire, in the vicinity of the Black Butte River and Bald Mountain.
On September 1, the complex had increased to 242,941 acres (98,315 ha), most of that in the combined Doe-Glade-Tatham-Hull fire, and was 20 percent contained. Firefighters were building containment lines along the west side of the Doe Fire and the south side of the Hull Fire. The Hopkins Fire had expanded to 7,472 acres (3,024 ha) with no containment. One firefighter was confirmed dead in a vehicle accident, and another was injured. Over the next few days, the fire continued to expand rapidly, burning about 20,000 acres (8,100 ha) a day, reaching 298,269 acres (120,705 ha) on September 4. Crews conducted back burns west of the Tatham Fire and northwest of the Hull Fire. Increased fire activity in eastern Mendocino County led to an evacuation warning for the Mendocino National Forest, north of Hull Mountain. On September 5, the National Weather Service issued a Fire Weather Warning due to high winds and unseasonably hot temperatures of 90 to 110 °F (32 to 43 °C). On September 6, aircraft dropped water and retardant on the Hopkins Fire, which had expanded to 15,466 acres (6,259 ha). Back-burns were conducted on the northwest side of the Doe Fire, in anticipation of extreme wind conditions. By September 7, the complex had increased in size to 349,565 acres (141,464 ha) and was 24 percent contained. A total of 1,138 personnel were working on the fire.