The 2017 Northern California wildfires from October 7 to October 14
The October 2017 Northern California wildfires, also known as the Northern California firestorm, were a series of 250 wildfires that started burning across the state of California, United States, beginning in early October. 21 of the wildfires became major fires that burned at least 245,000 acres (99,148 ha). The wildfires broke out throughout Napa, Lake, Sonoma, Mendocino, Butte, and Solano Counties during severe fire weather conditions, effectively leading to a major red flag warning for much of the Northern California area. Pacific Gas and Electric reported that red flag conditions existed in 44 of the 49 counties in its service area. Seventeen separate wildfires were reported at that time. These fires included the Tubbs Fire (which grew to become the most destructive wildfire in the history of California), the Atlas Fire, Nuns Fire, and others. These wildfires were also the most destructive ones of the 2017 California wildfire season. The October 2017 were the costliest group of wildfires on record, causing at least $9.4 billion (2017 USD) in insured damages, surpassing the 1991 Oakland firestorm, which until then had been the single costliest fire on record. In addition, the Northern California fires were predicted to cost the US economy at least $85 billion.
Owing to the extreme conditions, shortly after the fires ignited on October 8 and 9, they rapidly grew to become extensive, full-scale incidents spanning from 1,000 acres (400 hectares) to well over 20,000 acres (8,100 ha), each within a single day. By October 14, the fires had burned more than 210,000 acres (85,000 ha) while forcing 90,000 people to evacuate from their homes. The Northern California fires have killed at least 44 people and hospitalized at least 185, making the week of October 8, 2017, the deadliest week of wildfires in California history. Collectively, this event constitutes the largest loss of life due to wildfires in the United States since the Cloquet Fire in 1918. In total, an estimated 8,900 structures were destroyed.
Days prior to the wildfires, the National Weather Service had begun issuing red-flag warnings throughout much of northern California as conditions were expected to become extremely volatile, with winds expected to be gusting between 25 and 35 miles per hour (40 and 56 km/h) from the north to the south. By the evening of October 8, the Diablo winds were reported gusting up to 70 miles per hour (110 km/h) within the affected areas as over a dozen wildfires began to break out.