Illinois State Water Survey - University of Illinois at Urbana-Champaign
State Climatologist Office for Illinois
Illinois Growing Season
Days Between Last Spring and First Fall Frost (Occurrence of 32°F)
Jim Angel, state climatologist
The average length of the growing season varies from about 190 days in far southern Illinois to 160 days in far northern Illinois. Of course, the actual length can vary from year to year. Many perennials have growing seasons that last longer than these maps would suggest.
PDF version of this map (hi-resolution) (215k)
