The first half of September in Illinois has been both warmer and drier than average. The statewide average temperature is running about 2 degrees above the 30-year average.
The statewide average precipitation is at 0.92 inches, which is about half of the 30-year average through September 16. Of course that precipitation is not evenly distributed around the state. This snapshot below of the radar/raingauge product of the NWS for the last 14 days shows that parts of western, east-central, and northern Illinois received amounts of 1 to 3 inches of rain (shades of green and yellow). Meanwhile, large areas of the state have received far less than an inch of rain (shades of blue).
Here in Champaign-Urbana we have received a grand total of 0.22 inches for September. This follows on the heels of an August with only 0.36 inches. Carbondale, in the lighter shade of blue in southern Illinois, reported only 0.07 inches for September.
Dry as it is, the statewide average precipitation of 0.92 inches is only the fifth driest September on record and we still have half a month to go. The driest September on record was 0.49 inches back in 1979.