The Thomas Fire was a massive wildfire that traversed the forest within Ventura and Santa Barbara Counties . It was one of multiple wildfires that ignited in southern California in December 2017 . The unusually strong and persistent Santa Ana winds were the largest factor in the spread of the fire . The region experienced an on-and-off Santa Ana wind event for a little over two weeks , which contributed to the Thomas Fire 's persistent growths in size . At its height , the wildfire was powerful enough to generate its own weather , qualifying it as a firestorm
multiple wildfires
December 2017 Southern California wildfires
Los Padres National Forest