What you need to know about the heat wave in Death Valley. Death Valley, which runs along California's border with Nevada, has recorded the hottest temperatures on Earth, the highest being 134 degrees Fahrenheit in July of 1913. Heat records are being broken all throughout the southern US, with about one-third of Americans currently living under either a heat watch or a heat warning. Triple-digit temperatures are being recorded and June was the hottest on record, according to multiple weather agencies. What does this mean for the world? Most of the record breaking heat is being seen as human-caused climate change, and scientists predict that next year will be even hotter.