Climate Data - Metadata, Illinois State Water Survey

Illinois State Climatologist Data


Please read our Survey-wide Data Disclaimer before continuing.

Years of Coverage

The data contained in the Climatologist’s database spans from 1901 to 2017. Years of record vary from station to station.

This site provides monthly results, followed by a yearly total (in bold), and finally by season (listed in yellow). The four seasons are winter (December-February), spring (March-May), summer (June-August), and fall (September-November).

Provisional vs. Final Data

Data displayed in this database newer than 4 to 5 months are provisional. Earlier data are considered final. Provisional data have not been finalized by quality control standards at the National Climatic Data Center, and are subject to revision.

Climate Parameters Offered

There are 12 climate parameters offered on this web site. Additional climate parameters are available, and may be obtained by contacting the State Climatologist Office.

Climate Parameters Explained

The explanations of each climate parameter below have been simplified. For more detailed information, see the State Climatologist Web Site. All measurements are monthly.

  Precipitation - Amount of precipitation recorded, in inches.
  Rain Days - Number of days that rain occurred.
  High Temp - Average high temperature recorded, in degrees Fahrenheit.
  Low Temp - Average low temperature recorded, in degrees Fahrenheit.
  Mean Temp - Average mean temperature recorded, in degrees Fahrenheit.
  Snow - Amount of precipitation recorded as snow, in inches.
  Daily Max Precipitation - Highest amount of precipitation recorded during one day, in inches.
  Heating Degree Days - Determined by a formula. More Information
  Cooling Degree Days - Determined by a formula. More Information
  Days 90 - Number of days that the high temperature was at or above 90 degrees.
  Days 32 - Number of days that the low temperature was at or below 32 degrees.
  Snow Days - Number of days that measurable snow (0.1 inch or more) occurred.


Before data are added to the database, quality and accuracy checks need to be performed. For this reason, the database may not contain our most recent measurements. We will try to keep the database as current as possible, but if you need recent data, please contact the State Climatologist Office.

Reporting Errors

The following values denote errors for a given measurement.

  Precipitation: -9.99
  Rain Days: -99
  High Temp: -99.9
  Low Temp: -99.9
  Mean Temp: -99.9
  Snow: -9.9
  Daily Max Precipitation: -9.99
  Heating Degree Days: -999
  Cooling Degree Days: -999
  Days 90: -99
  Days 32: -99
  Snow Days: -99


The State Climatologist Office follows the same metadata standards as the Environmental Protection Agency. More information about metadata is available on their web site.

Illinois State Water Survey

2204 Griffith Dr., MC-674
Champaign, IL 61820-7463
Email us

Email the Web Administrator with questions or comments.

©2018 University of Illinois Board of Trustees. All rights reserved.
For permissions information, contact the Illinois State Water Survey.
Terms of use | Privacy Policy