CHAMPAIGN, Ill. — Cooler weather has led to lower soil temperatures in the first half of August in Illinois, according to Jennie Atkins, Water and Atmospheric Resources Monitoring program manager at the Illinois State Water Survey.
The second week of August brought cooler weather into Illinois with daily lows falling into the 50s in the northern and central regions. Soil temperatures at 4 inches under bare soil averaged 77 degrees on Aug. 15, 5 degrees lower than on Aug. 1.
However, this is equal to last year’s average and 3 degrees above the long-term average. Daily highs have reached the high 80s with lows in the 60s.
August has also been wet for certain areas of the state. More than 10 inches of rain has been reported at several stations in Stephenson County in northern Illinois, while an Effingham County station has received over 6 inches in the past two weeks.
However, the Illinois Climate Network station in Pike County has seen only 0.13 inches so far for the month. This variation in rainfall has caused soil moisture levels to vary greatly.
Overall, state soil moisture at 2 inches declined 4% over the first half of the month. Moisture levels in southern Illinois had the largest drop, falling 21% as the region dried out from a wet July.
The north saw an increase of 31%, thanks mainly to the rain in the northwest. Levels in central Illinois have seen little change so far this month as soil moisture in the east-central region remains near the wilting points of the soils monitored.
Similar patterns were seen at 4 and 8 inches, while moisture levels remained steady at depths of 20 inches and greater.
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 at www.isws.illinois.edu/warm.