Illinois Soil Temperatures – Then and Now

You can find 4 and 8-inch soil temperatures for Illinois on the Water Survey’s web site at These data are from a network of 19 sites around Illinois that is maintained by the Survey.
Below are the maps of what the 4-inch soil temperatures looked like on Wednesday and a year ago on the same date. This year the soil temperatures are barely above freezing in northern Illinois and barely above 40 degrees in southern Illinois. On the same date in 2012, the 4-inch soil temperatures were in the upper 50s and lower 60s across the state.

Cold March

I dropped my car off at the shop for some brake work this morning here in Champaign and decided to walk to work. The air temperature was 21 degrees and the wind chill was 4 degrees. That was an uncomfortable stroll even with a winter coat, hat, and gloves. A year ago this morning (March 20, 2012), the air temperature was 63 degrees and well on its way up to a high of 82 degrees, a record high for this date.
So far this year, the statewide March temperature is 33.3 degrees. A year ago through this date, the statewide temperature was 51.1 degrees. That’s a whopping 17.8 degree difference. March went on to become the warmest March on record at 55.3 degrees, 14.2 degrees above the long-term average monthly March temperature of 41.1 degrees.
The rest of March does not look promising. The 1-5 day forecast shows temperature 10 to 14 degrees below average for Illinois. The 6-10 and 8-14 day forecast show widespread cold weather across Illinois and the central US. Figures below.
The long-term average temperatures for March were calculated from the 1981-2010 period.

March Off to Cold, Wet Start

So far, March has been both colder than average across all of Illinois and wetter than average across western and northern Illinois. The statewide temperature for March 1-14 was 32.5 degrees, 5.4 degrees below average. That stands in stark contrast to last March when the statewide temperature for March 1-14 was 45.2 degrees, 7.3 degrees above average. That is a 12.7 degree difference between the two periods.
Precipitation through the morning of March 15 (Figure 1) ranged from less than an inch in southern Illinois to over 2 inches in western Illinois. Precipitation was below average in southern and eastern Illinois (Figure 2) and above average in western and northern Illinois. The dryness in southern and eastern Illinois is not a major concern at this point because of wet conditions in those areas in January and February.
The latest NWS forecasts show that rains of 1 to 2 inches or more could fall in the southern third of Illinois over the next five days (Figure 3). Also their 6-10 day and 8-14 days forecast show that colder and wetter than average conditions will prevail for the rest of March. Because of recent rains and melting snow, the NWS has issued flood warnings today on portions of the Mississippi, Illinois, and Wabash Rivers (Figure 4).

Figure 1.
Figure 1.

Figure 2.
Figure 2.

Figure 3.
Figure 3. Five-day precipitation forecast. Source:

Figure 4.
Figure 4. Flood warnings in Illinois.

April Colder Than March – A Rare Case


The statewide average temperature for April 2012 was 54.1 degrees, based on available data. The statewide average temperature for March was 55.0 degrees, based on the latest numbers from NOAA.  That means that April was almost a degree cooler than March. What makes this even more impressive was that the April temperatures are still 2.4 degrees above normal!
By the way, the statewide normal monthly temperature is 40.7 degrees for March and 51.7 degrees for April, an eleven degree rise.
How rare is it for April to be colder than March? In the statewide records that extend back to 1895, it happened only in 1907 when the March temperature was 47.0 degrees and the April temperature was 43.2 degrees. In all the other cases between 1895 to 2011, April was always warmer.
The highest temperature reported in the state for April was 92 degrees at Kaskaskia on April 2 and at Jacksonville and Pana on April 3. The coldest temperature reported was 23 degrees at Jerseyville on April 17.


The statewide average precipitation was 3.32 inches. That is about 0.5 inches below normal. The rainfall over the weekend was fairly widespread and helped much of the state. In general, the heaviest rains of 5 inches or more fell east of St. Louis. Meanwhile, rainfall amounts of 2 inches or less fell in far southern Illinois, far northwestern Illinois, and a large swath between Peoria and Kankakee. Those areas were 1 to 3 inches below normal for the month (second map).
The highest monthly rainfall total reported in Illinois for April was a CoCoRaHS observer near Belleville (IL-SC-3) with 8.64 inches. Some of the lowest monthly rainfall totals in the state were in Kankakee and Will Counties. For example, Grant Park (IL-KK-19) in Kankakee County reported all 30 days and only received 0.83 inches for the month.

April rainfall totals, based on a radar product developed by the National Weather Service. Click to enlarge.

April rainfall departure from normal, based on a radar products developed by the National Weather Service. Click to enlarge.