The Thomas fire started Dec. 4 in Ventura County. Fanned by strong and shifting wind gusts, the fire grew quickly during its first 24 hours and eventually became one of the largest wildfires on record in California.
The map above shows the fire's progression through Dec. 20. It quickly burned more than 63,000 acres through Dec. 5. Dark green shades indicate the first days of the firefight. The fire then flared up Dec. 10, burning nearly 61,000 acres.
As of Dec. 19, the fire burned more than 271,000 acres in Ventura and Santa Barbara countieIt has burned an estimated 271,000 acres, making it the third-largest wildfire in California history, behind only the 2003 Cedar fire and 2016 Rush fire.
Note: Click on the map or click here to see a larger view.
High fire risk is expected to last into January, adding to fears that months of deadly and destructive wildfire danger will extend into early next year. Cal Fire reported 6,982 fires in California from Jan. 1 to Dec. 17, including the devastating North Bay fires in October. Those fires scorched more than 505,900 acres, more than double last year’s burned acreage count. During that same period in 2016, the state firefighting agency reported 4,759 fires that burned 244,304 acres.
California's five-year average for wildfires during that time frame is 4,787 and 202,737 acres burned.
The significant increase in the numbers and size of fires is largely because the state is coming off one of its wettest winters in years in 2016-2017, which left hillsides covered in grass and other vegetation. That grass dried out in summer and turned into tinder, providing fuel for rapidly spreading fires often pushed by strong winds that can carry hot embers for miles and turn small spot fires into infernos.
An increase in the number of dead and dying trees also has exacerbated the wildfire threat, Cal Fire officials said. An estimated 129 million trees covering 8.9 million acres have died in California due to drought and bark beetle infestation, according to the USDA Forest Service.