The Grand Canyon National Park Service says Delphine Martinez, a resident of Window Rock, was on a multi-day backpacking trip on Sept. 4 when she was found unconscious along the Thunder River Trail, about one mile from the confluence of Tapeats Creek and the Colorado River.
"Trip members attempted resuscitation efforts without success," officials said.
The Coconino County Medical Examiner will determine Martinez's cause of death.
Temperatures in the inner canyon were over 100°F that day, and the high temperature at Phantom Ranch reached 115°F.
"Park rangers at Grand Canyon National Park urge visitors to Grand Canyon, especially inner canyon hikers and backpackers, to be prepared for excessively hot days in the coming weeks," officials said.
Officials urge people to not hike in the inner canyon between 10 a.m. and 4 p.m., as temperatures on exposed parts of the trail can reach over 120°F in the shade.
The Thunder River Trail and Tapeats Creek in Grand Canyon National Park. (Grand Canyon NPS)