The Okanogan Complex of wildfires has surpassed last year's Carlton Complex blazes and is now the largest in Washington state history.

Fire spokesman Rick Isaacson said Monday the Okanogan Complex was measured overnight at just over 400 square miles, slightly more than the Carlton fires, which also burned in Okanogan County. The fires cover 256,567 acres.

The latest group of fires grew by more than 26 square miles Sunday and is expected to spread even more in coming days.

Isaacson called the record unfortunate and notes it's only Aug. 24, meaning the fire could burn for several more months. Officials are still trying to determine how many homes and other structures have been burned.

About 1,250 people are battling the fires, which are 10% contained and threaten over 5,000 homes.

A Red Flag Warning remains in effect for much of central Washington through Tuesday evening, according to the National Weather Service. That includes the Okanogan and Methow Valleys, and the Okanogan Highlands.

MAP: Current wildland fires in Washington

The Okanogan Complex is made up of the 9 Mile, Beaver Lake, Twisp River, Lime Belt and Tunk Block fires.

More manpower joined the fight on Sunday, including an additional 200 Washington National Guardsmen bringing the total to 700.

Firefighters also arrived from New Zealand and Australia, and were expected to spend one day learning about current fire behavior and weather conditions before being assigned to one of the large fires burning in the Northwest.

"We don't pull this trigger easy," said Steve Gage with NIFC. "This is one of those tough decisions we make, and when we have a lot of fire and we have a lot of middle management and fire line positions that we need to fill and we can't fill them internally across the United States with 25,000+ firefighters we have committed in the efforts we do reach out to our international partners."

Central and Eastern Washington are dealing with 16 large wildfires that cover more than 920 square miles.

The State Department of Natural Resources said they were overwhelmed by volunteers, including many with skills that are not currently needed. They currently only need people with a current red card or who own and operate heavy equipment. They will offer blue card classes to equipment operators.

Learn how to volunteer

Red Cross shelters

Sterling Intermediate School, 600 N. James, East Wenatchee
Brewster Middle/High School, 503 S. 7th Street, Brewster
Columbia High School, 4961 Hunter Shop Rd., Hunters
Lake Roosevelt High School, 500 Civic Way, Coulee Dam
Loon Lake Elementary School, 4001 Maple St., Loon Lake
Morgen Owings Elementary School, 407 E. Woodin Ave, Chelan
Grace Evangelical Free Church, 851 S. Miner St., Colville

Social media has been key for emergency managers to get the word out quickly this week. A common phrase seen on many posts regarding evacuations is "Do not wait for door-to-door notification."

Okanogan County officials say there are several ways to stay up-to-date:

For the American Red Cross emotional support hotline, call 1-800-985-5990.