New weather data show the month of May was the hottest ever recorded in the contiguous United States, with temperatures that soared more than 5 degrees Fahrenheit above 20th century averages. Climate scientists say May’s heat toppled the previous record, set in 1934 at the height of the Dust Bowl, and is consistent with models for global warming. The record U.S. temperatures came as 2018 is on track to be Earth’s fourth-hottest year on record—while the five warmest years on record all have taken place since 2010.