As the snow turns to mud this week, this is a good time to advertise links for the soil temperatures in Illinois. The Water Survey operates a 19-station network of sites around the state collecting hourly soil temperatures at 4 and 8 inches under grass as well as an estimate under bare ground.
All this information can be found at the Illinois Climate Network Soil Data site. Below is just a screenshot of that page to show where you would find that information on the real web page.
Here is a snapshot of 4-inch soil temperatures as of 10 am, March 13, 2015. Soil temperatures are still near the freezing mark in the northern half of the state, but warm into the 40s and low 50s in the southern half of the state.