A weak cold front swept through Chicago during the lunch hour Monday, but once again, significant rain failed to materialize until the system was south and east of the city. O’Hare received no rain, while Midway collected only .08". Already the driest summer on record to date, a scant 0.2" of rain has fallen at O’Hare in the 7+ weeks since June 10. Meanwhile, heat statistics are adding up. O’Hare’s 91° and Midway’s 92° are the 13th and 19th days respectively of 90° days in Chicago this summer, more than the last two summers combined.
Monday’s cold front provides one day of relief from the ongoing heat. Another brief cold frontal passage is likely again on Thursday, with oppressive heat to follow over the weekend and into next week. Rain with frontal passage is likely on Thursday, but the computer models have not distinguished themselves and have consistently under forecast temperature and over forecast rain all summer.
O’Hare’s 97° on Sunday was the hottest day since 101° on July 31, 1999. Again, the heat was made more tolerable by low dew points. The heat should break on Monday with the passage of a cold front and a gradual shift to northwest winds—but the front is weak, and temperatures will remain above normal Tuesday.
Today, Chicago enters the warmest period of normal temperatures for the year, 10 days with an average a high of 84° and a low of 64°. After the brief heat relief, temperatures turn back up on Wednesday, climbing each day to follow and peaking around 100° next weekend.
Meanwhile, the extreme drought retains its grip on the area. Rain with Monday’s cold front will be scattered, and even the computer models are backing off on totals, predicting only a scant few hundredths of an inch. Thursday now looks like a better bet for rain as another weak cold front approaches from the northwest.