The Arizona wildfire started on July 4 and had burned for several days before exploding toward the North Rim and the Grand Canyon lodge.

U.S. land managers are racing the clock as hotter, drier weather raises the risk of wildfires in the nation’s overgrown forests with each passing year.

Arizona Governor Katie Hobbs has demanded an independent investigation into why National Park Service staff let the fire burn during the driest time of the summer in a botched attempt to reduce wildf...