As this chart indicates, July 2011 goes down in history at Indianapolis as the hottest month in 75 years, and is the 2nd hottest since weather records began in 1871. During the summer of 1936, the Midwest and much of the nation was in the middle of the epic Dust Bowl. A persistent upper level ridge of high pressure is to blame for the prolonged period of heat. Nearly every day of the month was at or above normal. Much of the second half of the month was near 10 degrees above normal, when the most intense heat waves impacted the area. Heat index values consistently ranged from the 100s to 110s across central Indiana during several periods in the second half of the month.
Several locations broke into the triple digits on the 21st. Indianapolis reached 100 on this day, which was the first time since August of 1988 (102 degrees). Many locations had impressive strings of consecutive days with maximum temperatures at least 90 degrees. Shelbyville and Eagle Creek both finished the month with 16 straight days of highs at or above 90 degrees, and Indianapolis had 15. Temperatures look to continue such a trend into early August, which would give Indianapolis a good chance of coming close to the record of 19 straight days set back in August of 1936.