"The air temperature soared to 109 degrees, and the reported dew point, a measure of humidity, was an astonishing 90 degrees late that afternoon. The corresponding heat index of 159 degrees is not even considered valid since the equation for computing it wasn’t designed for such extreme conditions."


http://www.washingtonpost.com/blogs/capital-weather-gang/wp/2015/08/03/chart-busting-heat-and-humidity-in-iran-city-were-completely-normal-says-local/