CHAMPAIGN, Ill., 8/17/23: A change in weather has cooled soils across Illinois in mid-August, according to Jennie Atkins, Water and Atmospheric Resources Monitoring (WARM) program manager at the Illinois State Water Survey.

Air temperatures have fallen across the state in the past few days, averaging 69 degrees on Aug. 15, 5 degrees below normal. Daily lows were in the 50s for most of northern and central Illinois. As expected, soil temperatures have declined with the weather. Temperatures at 4 inches under sod averaged 75 degrees on Aug. 15, 4 degrees lower than on Aug. 12. High temperatures reached the low 80s with lows in the high 60s.

Despite the drop, soil temperatures were only 1 degree lower than last year’s and equal to the long-term average.  

August has been wet for most of the state. Illinois has seen 3.59 inches of rain as of Aug. 15, 1.68 inches more than normal, which has caused soil moisture levels to rise. Levels at 4 inches have increased an average of 52 percent so far this month. The largest increases were in central Illinois, where moisture levels jumped 80 percent, with some locations receiving more than 6 inches of rain so far this month.

Soil moisture increases were seen in the first 20 inches of the soil column for most of the state.  

The Illinois State Water Survey’s WARM program collects hourly and daily weather and soil information at 19 stations across the state. Daily and monthly summaries can be found at the WARM website (warm.isws.illinois.edu/warm/).

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Media Contact: Jennie Atkins, Ph.D., (217) 333-4966, jatkins@illinois.edu