[1] 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.

[15] In total, the Northern California fires killed 44 people[2] and hospitalized at least 192 others,[16][3] making this one of the deadliest wildfire events in the United States during the past century.

[21] 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.

[20][8] Reinsurance broker Aon Benfield stated that these are the costliest wildfires in U.S. history, with an estimated eight billion U.S. dollars in insured losses.

[26] By October 12, the air quality in the city of Napa was ranked the poorest in the nation, due to high levels of particulates and ozone.

[27] By October 13, air quality in the city reached the "hazardous" level, the most dangerous on the Environmental Protection Agency scale.

[28] Visibility issues spurred the Federal Aviation Administration to implement a ground delay program at San Francisco International Airport, and nearly 280 flights were canceled over a three-day period.

[29] Over a week after the fires started, flights continued to be canceled and delayed due to poor visibility from the smoke.

Reportedly igniting near Cherokee Road, the fire quickly expanded from hundreds to thousands of acres within a few hours of burning as it threatened nearby Oroville and surrounding rural neighborhoods.

[24][43] In the Fountain Grove area numerous homes, the Fountaingrove Inn, the historic Round Barn, and a Hilton resort were destroyed.

[47] In January 2019 CalFire determined the Tubbs Fire was caused by incorrectly maintained electrical equipment owned by a private landowner.

[54] CAL FIRE Director Ken Pimlott discouraged premature speculation of causes, stating that, "The facts will come out when the investigations are done.