CHAMPAIGN, Ill., 5/18/21: Cooler weather led to a decline in soil temperatures in the first half of May, 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 63 degrees on May 16, 3 degrees cooler than last year and 2 degrees warmer than the long-term average. Temperatures declined the first 10 days of the month as the state experienced cooler than normal weather. On May 10, temperatures averaged only 55 degrees with lows in the 40s.

Soils across the state have been warming since then with an 8-degree increase between May 10 and 16. Highs on May 16 reached into the 70s.

Soil moisture at 4 inches rose the second week of May due to rain throughout the state on May 8 and 9. Levels have declined since then to an average of 0.30 water fraction by volume (wfv) on May 16. 

The largest changes occurred in northern Illinois, where moisture levels were near the soils’ wilting points at the beginning of the month. Soil moisture has risen 26 percent on average so far in May though conditions remain dry in the region.

Moisture levels remained high at depths from 20 inches to 5 feet.

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). 

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