These observations are taken by the Illinois State Water Survey, located near the corner of Windsor Road and First Street in Champaign using a variety of weather instruments. Real-time conditions at this site are reported here.
The daily and monthly data, including departures from average and seasonal snowfall and degree days, for Champaign-Urbana are found in the first 4 links. Farther down are the archives going back to 1996. On February 3, 2017, we discovered an error in the normal monthly HDD total for January and will correct the appropirate forms. This will not impact the HDD accumulations but will change the departures from normal calculation.
The "Daily Summaries by Month" PDF are generated directly from the spreadsheet in "Current Data".