CHAMPAIGN, Ill. – Warmer weather has led to warmer and drier soils in Illinois, according to Jennie Atkins, Water and Atmospheric Resources Monitoring (WARM) Program manager at the Illinois State Water Survey, Prairie Research Institute, University of Illinois.
Soil temperatures rose 6–9 degrees, on average, across the state the first half of June. Temperatures at 2 inches under bare soil had a state average of 84.4 degrees on June 15, 5.8 degrees above the 2015 average. Several locations had daily maximums of 100 degrees or higher last week. Central Illinois had the highest regional average with 85.9 degrees on June 15. Southern and northern Illinois averaged 84.7 and 80.7 degrees, respectively.
Temperatures were slightly lower at depths of 4 inches with an average of 82.8 degrees on June 15 or 9.2 degrees above the long-term average. Under sod, temperatures averaged 73.0 at 4 inches and 71.9 at 8 inches, 5.9 degrees and 5.0 degrees, respectively, above the state's long-term average.
The higher soil temperatures and drier weather caused soil moisture levels to decrease. Moisture levels at 2 inches declined on average 35 percent between June 1 and 13 to 0.23 water fraction by volume (wfv). Rains moving through northern and central Illinois on June 14 and 15 led to an increase in soil moisture in those areas. On average, soil moisture levels averaged 0.27 wfv on June 15, a 23 percent decrease from the first of the month.
Moisture levels saw similar declines at the 4- and 8-inch depths. Moisture levels, however, remained high at 39 and 59 inches with state averages of 0.44 and 0.42 on June 15.
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).
