Illinois soils are warmer, drier in mid-July

[July 18, 2019]    Soils in mid-July are continuing to warm across the state, surpassing average temperatures from last year, according to Jennie Atkins, Water and Atmospheric Resources Monitoring (WARM) Program manager at the University of Illinois’ Illinois State Water Survey.

Soil temperatures at 4 inches under bare soil rose 4 degrees in the first half of July to a statewide average of 86 degrees. Temperatures were 8 degrees above the historical normal and 3 degrees warmer than last year on July 14. Daily highs are in the 90s for most areas with several locations measuring temperatures 100 degrees and higher.

Soil moisture levels have been falling in July, especially at depths down to 8 inches. Moisture levels declined 32 percent at 2 inches, averaging 0.23 water fraction by volume (wfv) on July 14. Similar but smaller declines also occurred at 4 and 8 inches, decreasing 25 and 22 percent, respectively.

Moisture levels remain high deeper in soils. Soil moisture at 39 and 59 inches showed no significant changes so far in July, averaging 0.47 and 0.44 wfv, respectively, on July 14.

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.

[Lisa Sheppard]