"The reason for this incredible heat has been the location of the jet stream, a thin river of air miles high that guides the path of potential storms," said Anthony Sagliani, Meteorologist for AccuWeather.com. "Unusually strong high pressure developed over much of the central part of the nation. This high pressure pushed the jet stream much farther north than usual, and there was virtually no chance of rain," said Sagliani. Additionally, since there was no rain and less moisture for the sun's energy to evaporate, most of the power went into heating the ground, and the result was weeks of searing heat."
Illinois Average July Temperatures Illinois Average July Rainfall 1936: 83.1 ºF 1930: 1.02 inches 2012: 81.8 ºF 1916: 1.23 inches 1901: 81.7 ºF 1936: 1.24 inches 1934: 81.3 ºF 2012: 1.47 inches 1916: 80.4 ºF 1914: 1.51 inches
"I think July 1936 still wins the prize as the most miserable month in Illinois records with the hottest temperatures and the third driest rainfall total," said Angel. "My dad says he remembers sleeping outside that July on the family farm in western Illinois near Nebo because the house was too hot."
Angel said this month looks to be another hot and dry one. "The NOAA Climate Prediction Center has updated their forecast for August. It’s not good news for Illinois with an increased risk of above-normal temperatures and below-normal precipitation."
In the pic: NOAA's three month temperature forecast.