Champaign, Ill. - Soil temperatures are above normal in mid-July, 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 at depths of 4 inches under bare soil averaged 79.9 degrees on July 15, 2.1 degrees above the long-term average. Soils were warmer than normal for all but one day in the first half of July as daily high temperatures reached into the 90s and above. In the sandy soils of Mason County, temperatures above 100 degrees were measured.
Temperatures were slightly cooler under sod. At depths of 4 inches, soils averaged 78.3 degrees on July 15, 0.9 degrees above the long-term average. Daily highs were in the 90s throughout the state.
On average, soil moisture changed little during the first half of the month in Illinois. However, localized rainfall led to large variations in soil moisture levels. A monitoring station in Warren County near Monmouth has had a 52 percent increase at the 2 inch depths so far in July. Other locations have had declines of more than 15 percent as moisture levels approached wilting points.
Soil moisture remained high at depths greater than 39 inches with little change in July.
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).