The fire burning in north-central Washington is now the largest in state history.
The Okanogan Complex of wildfires has surpassed last year's Carlton Complex blazes.
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 latest group of fires grew by more than 26 square miles Sunday and is forecast to spread even more in coming days.
Officials are still trying to determine how many homes and other structures have been burned.
About 1,250 people are battling the fires. Last week, three firefighters were killed and four injured near Twisp, Wash.
See Tuesday's Arkansas Democrat-Gazette for full details.