The Cram Fire exploded to 28,000 acres on July 15, shut down Highway 97 north of Madras and has degraded air quality in central Oregon.

Gusty, shifting winds and high temperatures have caused a wildfire in central Oregon to spread rapidly, reaching more than 40,000 acres and prompting evacuations from ranches and communities in two counties, the authorities said on Tuesday.

Hot, dry conditions and strong winds have made it difficult to contain the Cram fire, the largest active wildfire in the state.