A wildfire that has been burning in in Yosemite National Park’s backcountry for weeks forced the evacuation of 100 visitors via helicopters on Sunday. The evacuees included hikers climbing Half Dome, which is 5,000 feet above the Yosemite Valley. Some had to be airlifted from other hiking trails and campgrounds. Firefighters had been monitoring the flames, but “We just got unbelievable crazy winds and unexpected hot conditions,” said the park’s chief of road and trails, Tim Ludington. “The fire behavior totally changed.” So far, the uncontained fire has burned through 700 acres.