If you thought the worst of the summer's sweltering temperatures were behind us, think again. Some schools closed early as the late-August heat wave gripping Ohio brought temperatures not seen in ...

Add Yahoo as a preferred source to see more of our stories on Google. "It's not the heat, it's the humidity." Actually, it's both, and that's where the National Weather Service's heat index comes in.

The heat index, or apparent temperature, combines air temperature and humidity to indicate how hot it feels to the body. High humidity slows sweating, the body's natural cooling system, making ...

The heat index, or apparent temperature, combines air temperature and relative humidity to indicate how hot it feels. High humidity slows sweating, the body's natural cooling system, making ...

Add Yahoo as a preferred source to see more of our stories on Google. The sticky combination of heat and high humidity can be more than uncomfortable -- it can be deadly. Mario Tama/Getty Images ...

The heat is on in Alabama, and it's only getting hotter. The heat index is expected to climb sharply from Monday, June 2, through Monday, June 9, pushing conditions into potentially dangerous ...