(The Center Square) – The Dixie Fire, the second-largest recorded wildfire in California history, burned nearly 500,000 acres as of Sunday.

Burning northeast of San Francisco above the Cresta Dam and Feather River Canyon, the Dixie Fire expanded from 274,000 acres last week to now more than 489,287 acres, or 764.5 square miles, the California Department of Forestry and Fire Protection says.

The fire has been raging for 26 days and is only 21% contained, with weather conditions expected to make matters worse.

The area that has been destroyed is larger than the geographic region of Houston, Texas, the fourth-largest city in the U.S.

The fire is spreading across four counties after strong southwest winds, low humidity and warm temperatures are making matters worse in two zones where the fires are blazing.

The Dixie Fire West Zone is where fire has been active in areas of clear sky, calm winds, and moderate recovery of relative humidity.

“Crews will continue to fight the fire aggressively, construct direct, and indirect line to secure the fire perimeter,” Cal Fire says. “All resources are committed to structure defense in affected communities.”

In the Dixie Fire East Zone, fire behavior is expected to increase with clear air and a warming trend that is forecast to peak mid-week, the state says. “Fire behavior continues to be moderated in the existing fire scars so firefighters have focused on constructing and reinforcing containment lines bridging the Sheep and Walker fire scars,” Cal Fire says.

More than 5,000 firefighters are currently fighting the fire and three have been reported to be injured.

"We're seeing fire activity that even veteran firefighters haven't seen in their career," Edwin Zuniga, a spokesman for the California Department of Forestry and Fire Protection, told the Washington Post.

The August Complex Fire of 2020 consumed more than 1 million acres, which if the Dixie Fire isn’t contained, it could surpass.

The fire has damaged 42 residential, commercial and other structures, destroying 627 entirely, the state agency notes.

The cause of the fire has not yet been confirmed and is under investigation. However, Pacific Gas & Electric said a tree falling on one its power lines could have caused it. On Friday, a federal judge order the company to provide more information by Aug. 16.

Evacuation warnings and mandatory evacuation orders are constantly changing and being issued by county.

There are currently over 50 evacuation orders and roughly 10 evacuation warnings detailing roads, towns, counties and neighborhoods impacted. More than 40 zones are listed by number as well as informational resources by county and sheriffs’ departments.