On a late July morning, the sun is already broiling the National Mall in Washington, D.C. The air is so humid, even a loose shirt quickly turns into a sticky mess. Later, the heat index will top out ...

Jeffrey Pagulong and his son Christof stand in front of the Lincoln Memorial in Washington, D.C., on July 29. Pagulong, who is visiting from Boston, said his neck fan "helps a lot" in the high ...