Through August 20th, 18.39" of rainfall have been observed at Chicago-O'Hare in meteorological summer (June 1-August 31) so far, which means that this summer is already the 5th wettest summer on record in Chicago. Records have been kept since 1871. The 1871-2010 seasonal normal rainfall total through this date is 10.45". With a frontal system moving through the region on Tuesday, there is good chance for showers and thunderstorms, and thus a good chance to add to this rainfall total and continue to move up in the rankings. Below is an updated list of the top-10 wettest summers in Chicago, including this summer's total through August 20th.