a Fire Weather Warning due to high winds and unseasonably hot temperatures of . On September 6, aircraft dropped water and retardant on the Hopkins Fire, which had expanded to . 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 and was 24 percent contained. A total of 1,138 personnel were working on the fire. On September 8, evacuation orders remained in place for western Glenn County and eastern Mendocino County, and had been expanded to parts of northern Lake County. Strong Diablo winds continued to drive fire activity, but helped clear smoke westward, allowing for increased aircraft operations. During September 8–9, the fires grew rapidly, driven by strong east winds. The complex increased in size to , with the Hopkins Fire accounting for . On September 9, the Elkhorn Fire merged with the Hopkins Fire, and the combined fire was assigned to the Elkhorn Fire incident and no longer managed as part of the August Complex. On the same day, the southern front of the Elkhorn Fire merged into the northern perimeter of the Doe Fire in southwest Tehama County, but the August Complex and the Elkhorn Fire continued being managed as separate incidents, in order to have the separate incident teams focus on their individual fire areas. On September 10, the August Complex jumped containment lines on the southwest, crossing the Black Butte River and moving into the Yuki Wilderness, triggering evacuations in Lake County, north of Lake Pillsbury. On the morning of September 10, the August Complex was estimated at , making it the largest fire complex in California history, surpassing the 2018 Mendocino Complex Fire, which had burned in the southern part of the Mendocino National Forest. On September 10, the combined Elkhorn and Hopkins Fires were being managed jointly as the Elkhorn Fire, which had burned . The fire rapidly advanced into the Six Rivers National Forest, jumping the canyons of the Mad River and North Fork Eel River, before crossing the Eel River south of Alderpoint. Evacuations were ordered in Humboldt County from Bridgeville south to Fort Seward and Alderpoint, while areas from there west to U.S. Highway 101 received an evacuation advisory. On the evening of September 10, the August Complex and Elkhorn fires had merged into a single, massive wildfire with an area of