The NWS warning was in effect for regions of the Grand Canyon below 4,000 feet elevation. Temperatures were forecast to potentially reach 110 degrees at Phantom Ranch and 102 at Havasupai Gardens.

The rash of global heat waves across the Northern Hemisphere comes as average global temperatures continue to climb, driven by the burning of fossil fuels. Last year was the hottest year in recorded history, and new data reveals that the world is becoming hotter, faster.

Six tornadoes were reported from Wisconsin to Indiana on Wednesday, with the Wisconsin ones labeled as “large,” though no major damage or injuries have been reported.

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.

After a 67-year-old hiker dies in the Grand Canyon, authorities warns of heat-related illness due to daytime temperatures in excess of 120°F

The National Parks Service warns daytime temperatures at the Grand Canyon can top 120°F, ‘significantly increasing the risk of heat-related illness’