At least 8.5 million acres have been torched by wildfires so far this year across the United States, according to data from the National Interagency Coordination Center — about 2.1 million acres above the 10-year average of 6.3 million acres burned by this point in the year. California has been particularly hard hit. Data: National Interagency Coordination Center; Note: Cumulative counts are sometimes revised, causing short-lived spikes or dips in the number of acres burned; Chart: Axios VisualsThe big picture: California's Camp Fire, the deadliest wildfire in the state's history, has burned more than 140,000 acres so far and claimed at least 56 lives. It was only 40% contained as of Thursday morning. It's already historic in both its size and destructiveness, having burned over 8,500 homes. California's fire siege has resulted from a combination of one of the state's hottest years on record, combined with extraordinarily dry vegetation along with frequent bouts of strong winds.Go deeper: California's Camp Fire is state's all-time deadliestWildfires are burning longer and hotter each yearWhy it's so hard to issue a fire warning