Heavy rain on July 17, 1996, produced several rainfall records and was the second most costly weather disaster in Illinois history. The 16.94 inches recorded at Aurora still stands as the statewide record for the most rain from a single 24-hour period. The 10.99 inches on the west side of the Chicago metro area was the most ever recorded in the Chicago urban area. Just as impressive as the point values was the size of the area covered by heavy rainfall. It was estimated that 16.3 inches fell over the wettest 100 square mile area of the storm, 12.6 inches over the wettest 1000 square mile area, and 5.2 inches over the wettest 10,000 square mile area. Another way to look at it is that an area of 1350 square miles exceeded the expected 100-year, 24-hour storm while 4650 square miles exceeded the expected 10-year, 24-hour storm for northeast Illinois. The widespread heavy rains led to excessive flooding. Damage estimates were on the order of 700 million dollars or more than 1.1B in 2020 dollars. FEMA estimated that more than 35,000 residences were flooded.
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