CHAMPAIGN, Ill., 4/20/23: Cooler weather in mid-April has caused Illinois soil temperatures to fall, according to Jennie Atkins, Water and Atmospheric Resources Monitoring (WARM) program manager at the Illinois State Water Survey.

Soil temperatures at 4 inches under bare soil averaged 49 degrees on April 17, 5 degrees cooler than historically. For the first two weeks of the month, however, soils were warmer than normal. Warmer weather in the second week of April led to highs reaching the low to mid-70s.   

Cooler weather at the beginning of the third week caused temperatures at 4 inches under bare soil to fall 15 degrees by April 17 with lows in the 40s.

Soils have also been drying out in April. Moisture levels at 4-inch depths declined 16 percent in the first half of the month to an average of 0.32 water fraction by volume (wfv) on April 17. The greatest declines were in central Illinois where moisture levels were 23 percent lower in mid-April.  

Southern Illinois saw a 9 percent decrease to a regional average of 0.38 wfv. For the first three months of 2023, parts of the region reported precipitation totals 6 to 8 inches more than normal. Even with the drying conditions experienced this month, moisture levels are at or above field capacity in the monitored soils.

Soil moisture remains high at depths of 20 inches and greater, showing little change from the beginning of April.

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/).

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Media contact: Jennie Atkins, Ph.D. - (217) 333-4966, jatkins@illinois.edu