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Soil temperatures at depths of 4 inches under sod averaged
67.5 degrees in Illinois on May 15, 5 degrees higher than the
long-term average. Daily highs were in the 60s and 70s for most
of the state.
Temperatures began the month 3 to 5 degrees cooler than normal
as they fell back into the 40s in northern Illinois. However,
temperatures have been steadily rising since the first week.
Southern and west-central Illinois had the highest regional
temperatures at 69 degrees on May 15. The coolest were in the
north with an average of 63 degrees.
Under bare soil, temperatures were slightly higher, averaging 73
degrees on May 15 as temperatures reached into the 90s in
central and southern Illinois.
Rainfall has been higher than normal so far for May as the state
received 0.73 inches above the long-term average. Despite the
wet conditions, soil moisture has been declining from the highs
seen at the end of April. Soil moisture levels at 2 inches
averaged 0.32 water fraction by volume (wfv) on May 15, a
decrease of 26 percent from May 1. Soils were wettest in the
south with an average of 0.35 wfv. West-central Illinois was the
driest at 0.28 wfv.
Similar, but smaller, declines have occurred at 4 and 8 inches.
Soil moisture remains high at depths of 20 inches and deeper
with no significant changes over the month.
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 A. Sheppard]
The Illinois State Water Survey at
the University of Illinois at Urbana-Champaign, a division of
the Prairie Research Institute, is the primary agency in
Illinois concerned with water and atmospheric resources.
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