CHAMPAIGN, Ill., 8/18/21: Soil temperatures have decreased in mid-August as cooler weather moved into the state, according to Jennie Atkins, Water and Atmospheric Resources Monitoring (WARM) program manager at the Illinois State Water Survey.

Soil temperatures at 4 inches under sod averaged 76 degrees on Aug. 15, 2 degrees lower than last year and 1 degree higher than the long-term historical average. Temperatures rose slowly the first 10 days to daily highs reaching the low to mid-90s. However, cooler weather across Illinois the end of last week caused soil temperatures to fall 4 degrees by Aug. 15.

Under bare soils, 4-inch temperatures reached into the high 90s in central and southern Illinois but cooled to a state average of 77 degrees on Aug. 15.

Soil moisture showed no overall change on average in the first half of August. Moisture levels declined the first week of the month but recovered the second week as all regions of the state saw rain.

Northern Illinois remains drier than other parts of the state. Soil moisture for the region averaged 0.22 water fraction by volume at the 4-inch depths on August 15, 25 percent less than in southern Illinois and 41 percent lower than in east central Illinois. There has been no improvement in the region in the last month.

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 (http://www.isws.illinois.edu/warm/) and in the Illinois Water and Climate Summary (http://www.isws.illinois.edu/warm/climate.asp).

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