KENSINGTON, Maryland — The contiguous United States sizzled to its hottest month ever last month, according to the National Oceanic and Atmospheric Administration. July averaged 76.89 degrees Fahrenheit across the Lower 48 states, eclipsing the Dust Bowl’s July 1936 by an eighth of a degree. The biggest driver of the record heat was nighttime lows that smashed the old mark for hottest minimums by 0.7 degrees, NOAA said. Hotter nights are a classic sign of human-caused climate change, according to scientists and several studies in peer-reviewed literature. Because of climate change, Masters said, “this may be one of the coolest years we’re gonna experience for the rest of our lives.”