Heat waves are more dangerous than tornadoes, statistically. They kill more people than sharks, and put more human lives at risk than blizzards, floods or lightning storms. But they lack a certain dramatic flair, making it surprisingly difficult for many people to grasp and evaluate the real danger lurking behind their devastating effects. Recognizing those risks could be a matter of life or death – especially as a changing climate is making dangerous extreme heat events more and more likely every year in the United States.