Illinois State Climatologist (Illinois State Water Survey)
- Monthly Data By Station Monthly summaries of precipitation, temperature (high, low, mean), heating and cooling degree days, and more from 117 stations throughout the state. Coverage is 1901 to date; date range varies by station.
- Current Climate Conditions for Illinois Maps summarizing precipitation or temperature for the last 7, 30, or 90 days, current month to date, or current year to date.
- Daily Observations for Champaign-Urbana, 1996 - date Daily observations and monthly summaries from the ISWS monitoring station. Covers 1996 to date.
- Illinois Climate Normals (1981-2010) 30 year average high, low, average temperatures and precipitation, calculated from NOAA data, based on 1981-2010.
Water and Atmospheric Monitoring Program (Illinois State Water Survey)
- Illinois Climate Network - Data By Station Latest temperature, precipitation, and wind speed and direction conditions from 19 Illinois Stations. For individual stations, you can download daily data from ~1989 - date (coverage varies by station).
- Shallow Groundwater Wells Network Depth to water for 35 stations in Illinois ~1950s to date, date range and reporting frequency varies by station.
- Illinois Climate Network: Soil Data Soil temperature and moisture data from 19 stations throughout Illinois
Midwest Regional Climate Center (Purdue University)
- cli-MATE online data portal Hourly and Daily data are available for download. Data from stations throughout the U.S. are available, with coverage from the 1800s to date. Years of coverage varies by station. Free registration is required.
- Midwest Climate Watch Daily, 7-day, 30-day, and month-to-date maps of temperature, precipitation, snowfall, snow depth, and growing degree days, as well as maps for prior months and seasons.
Illinois Precipitation Monitoring Networks
- Cook County Precipitation Network Daily data archive from 1989 to date, plus 10 minute and hourly readings for recent days.
- Imperial Valley Precipitation Network Daily data are available from 1992-2016 from 20 stations.
Historical Weather Records for Illinois
- Fort Armstrong Weather Records 1820-1836 Earliest known weather records for Illinois. Scanned from originals owned by the Rock Island Arsenal museum, and posted online by the Illinois State Climatologist
- Illinois Weather Station Observations 1862-1948 Station observations for Illinois from the National Cooperative Observer Program and its predecessors, in the University Archives
- Substation Meteorological Records Ottawa, IL, 1865-1874 Digitized records from the Ottawa substation
- Original monthly record of observations at LaSalle, Illinois, 1910-1912 U.S. Department of Agriculture, Weather Bureau
