CHAMPAIGN, Ill. - Soil temperatures declined through the first half of November, but still remain higher than normal, according to Jennie Atkins, Water and Atmospheric Resources Monitoring (WARM) Program manager at the Illinois State Water Survey, Prairie Research Institute, University of Illinois.
On November 15, soil temperatures at depths of 4 inches under bare soil averaged 49.4 degrees in Illinois, a decline of 13.3 degrees from November 1. Temperatures on November 15 ranged from a daily high of 59.3 degrees at Freeport to a low of 42.2 degrees in Carbondale.
Despite the decrease, temperatures remained higher than the long-term average. Historically, soil temperatures are approximately 8 degrees cooler in mid-November. The higher soil temperatures track the trend seen with the current air temperatures. Illinois air temperatures were 6.3 degrees above the long-term average on November 15. The National Weather Service is predicting cooler weather for the state this weekend and early next week. Lower soil temperatures should follow.
Soil moisture peaked on November 3 after the rains that fell on most of the state the first days of the month. Since that time, soil moisture at 2-inch depths have declined an average of 18 percent as of November 15. Similar trends were seen at 4- and 8-inch depths.
Though drier, soil moisture remained above the wilting points. Levels statewide averaged 0.28 water fraction by volume (wfv) at 2 inches, 0.29 wfv at 4 inches, and 0.30 wfv at 8 inches on November 15. Soils remained wetter at the deeper depths with averages of 0.42 and 0.41 wfv at depths of 39 and 59 inches, respectively.
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).
