A firefighter combats the King fire Sept. 22. (Marcio Jose Sanchez/AP)

A huge California wildfire that is larger than the entire city of Las Vegas is still growing, and authorities are warning that upcoming weather could lead to additional problems.

Thousands of firefighters are combating multiple blazes in the state. Most of them are fighting the King fire, which began Sept. 13 east of Sacramento and which is the largest wildfire in the state.

This blaze, which is sweeping across steep terrain and national forests, had grown to cover more than 89,500 acres (or about 139 square miles) by Tuesday, which means it has burned an area larger than cities such as Detroit, Philadelphia and Atlanta. (The fire is so sizable you can clearly see it from space.)

By Tuesday, the King fire was about 35 percent contained, nearly double the containment level reported a day earlier, according to California Department of Forestry and Fire Protection (or Cal Fire).

Weather forecasts hinted at possible problems in the coming days, however. The National Weather service issued a Red Flag warning through Wednesday night, covering portions of the area around the fire. A combination of wind gusts, warm temperatures and low humidity could “provide an environment for rapid fire spread,” the NWS said.

Cal Fire and the NWS both warned about “extreme fire behavior” stemming from these conditions. It is expected that the fire will be very active Tuesday and Wednesday along its northern and western portions, Cal Fire said.

Combating the King fire Monday. (Marcio Jose Sanchez/AP)

There are more than 7,300 firefighting personnel deployed to fight the King fire. This particular blaze has largely burned land in the Eldorado National Forest, but it has also destroyed 10 homes and nearly two dozen other structures. An additional 21,000 buildings — more than half of them homes — are still threatened.

Last week, the King fire nearly tripled in size in about a day (jumping from about 27,000 acres Wednesday to 73,000 acres Thursday). While it has continued to grow, it has not seen a similar surge in growth since that day.

Police arrested Wayne Allen Huntsman on Wednesday and charged him with arson in connection with the King fire.

Meanwhile, there are four other major wildfires burning in the state. That number is down from 10 such fires Thursday as authorities have reported containing other blazes. The Nelson fire, which had burned 62 acres in Mendocino County, was contained Monday afternoon, Cal Fire said.

Gov. Jerry Brown (D) declared a state of emergency due to the wildfires, which have been fueled by the endless drought that is ravaging the state. This year, Cal Fire has responded to nearly 5,000 wildfires, an increase of more than 1,000 over average years, officials said.

The northern edge of the King fire on Monday. (Max Whittaker/Reuters)