The White Sage Fire burns near Jacob Lake, Arizona on Thursday. The fire has already burned about 1,000 acres, prompting evacuations in the area. Grand Canyon National Park also closed the park's North Rim "until further notice." (Bureau of Land Management)

The NPS recommends avoiding hiking the Grand Canyon's inner trails between 10 a.m. and 4 p.m., when temperatures are at their peak. Temperatures in the inner canyon can reach over 120 degrees Fahrenheit in the shade, creating "extremely hazardous conditions for hikers," the NPS said.

In near 100 degree summer heat, two runners braved the trek of a lifetime in solidarity and support of a Chloride resident who is fighting her battle with cancer for