The final week of astronomical summer will feel quite summery in Chicago with Monday’s forecast high of 88 degrees at O’Hare running 12 degrees above normal for the date. While the warmth will be felt in inland locations, areas lakeside will feel as much as 8 to 10 degrees cooler.
Sunday, Sept. 22 will mark the Autumnal Equinox, the point when day and night will be approximately equal in length
While meteorological seasons are based on the calendar months, the astronomical seasons are defined by the position of Earth in its orbit around the Sun. The Autumnal Equinox will occur next Sunday at 7:43 a.m. CDT, marking the start of the astronomical fall season.
