CHICAGO, Illinois - After August opened with soaking downpours, summer storms in Chicago could disrupt everything from weekend plans to air travel across one of the nation's busiest transportation hubs. With heavy rain soaking tens of thousands of music fans at Lollapalooza in Grant Park, August got off to a soggy start in Chicago. While O'Hare International Airport often grabs the headlines, prediction market traders are focused on the official precipitation measurements recorded at Chicago Midway International Airport. According to NOAA's official 1991–2020 climate normals for Chicago Midway Airport, the average precipitation in August is about 4 inches. That official monthly total will determine how the market settles.