A backpacker who was hiking through the Grand Canyon over the weekend has died from what park rangers believe to be heat-related causes as the high temperature where she was walking hit 115°F.

The incident occurred at approximately 1:15 p.m. on Sunday, June 20, when backpacker, 53-year-old Michelle Meder of Hudson, Ohio, was on a multi-day backpacking trip from Hermit to Bright Angel Trail and the Grand Canyon Regional Communications Center received a report of a backpacker experiencing heat illness on the Tonto Trail near Monument Creek, according to a statement from the National Park Service (NPS).

“Hiking down the Hermit Trail on June 19, [Meder] became disoriented and later unconscious,” the NPS said in a statement regarding the incident. “On June 20, responding rangers determined Meder to be deceased; the cause of death is believed to be heat-related. On June 20 the high temperature at Phantom Ranch was approximately 115°F (46°C).”

The National Park Service warned in the statement that hiking in extreme heat can lead to “serious health risks including heat exhaustion, heat stroke, hypothermia, and death,” and that need to be aware that, should they run into trouble while hiking, efforts to help them could be delayed during the summer months due to “limited staff, the number of rescue calls, employee safety requirements, and limited helicopter flying capability during periods of extreme heat or inclement weather.”

An investigation into Meder’s death is now being conducted by the NPS in coordination with the Coconino County Medical Examiner to determine what exactly happened.

“Park Rangers at Grand Canyon National Park are strongly urging visitors to Grand Canyon, especially inner canyon hikers and backpackers to be prepared for excessively hot days in the coming weeks,” said the NPS. “In the summer, temperatures on exposed parts of the trail can reach over 120°F (49 °C) in the shade. Park rangers do not advise hiking in the inner canyon between the hours of 10 a.m. and 4 p.m. Most of the people who need emergency medical help in the canyon due to heat illness are hiking between these hours.”

Grand Canyon trails do not close due to inclement or hot weather and the NPS advised that there are ways to safely traverse the trails as long as you are prepared, well-acclimated to the climate and elevation, have the appropriate gear and have prior experience hiking in steep, desert terrain.