An extremely moist, tropical air mass has taken the entire eastern United States hostage. During this spell of high humidity, afternoon temperatures are generally not forecast to be record-breaking. The superfluous atmospheric moisture pouring into the eastern United States has two primary effects: 1. This is no ordinary deep tropical air mass. The humidityDew points, which are direct measures of humidity, are unusually high over such a large area.

Source: Washington Post August 11, 2016 16:51 UTC