Soil Temperatures Higher than Normal in Mid-September

[September 20, 2016]    Soil temperatures in Illinois are averaging 3 to 5 degrees above the long-term averages, according to Jennie Atkins, Water and Atmospheric Resources Monitoring (WARM) Program Manager at the Illinois State Water Survey, Prairie Research Institute, University of Illinois.

Higher air temperatures throughout the state have led to warmer soils. On September 14, average temperatures ranged from 75.8 degrees at 2 inches under the bare soil to 73.2 degrees at 8 inches under the sod. Daily maximums are reaching into the upper 80s, and low 90s as minimum temperatures remain in the mid-60s. Overall, soils are averaging 3 to 5 degrees warmer than normal for the middle of September.

Soils are currently drying out from the rains that fell across Illinois on September 7–10 that brought 2.02 inches to the state. Two-inch moisture levels in east-central Illinois doubled over the four days as the region received 3.02 inches of rain. Similar but smaller increases were seen in the state’s other regions.

Overall soil moisture at 2, 4, and 8 inches has increased or remained steady the first two weeks of September in all regions except northern Illinois where levels have decreased 17 percent on average from September 1.

Soils remain wet at the deeper depths with the 39- and 59-inch moisture levels near or above the field capacities.

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]