A wildfire in California grew to the largest the state has seen yet this year, as firefighting crews braced for thunderstorms and hot, windy conditions.

The McKinney Fire was burning out of control in northern California’s Klamath national forest, near the Oregon border, with expected thunderstorms a big concern, said US Forest Service spokesperson Adrienne Freeman.

“The fuel beds are so dry and they can just erupt from that lightning,” Freeman said. “These thunder cells come with gusty erratic winds that can blow fire in every direction.”

The blaze exploded in size to reach more than 80 sq miles (207 sq km) by Sunday evening, just two days after erupting in a largely unpopulated area of Siskiyou county. At least 2,000 people were ordered to evacuate. The cause of the fire was under investigation.