Deconstruct SunIllinois Hardiness Zones
Illinois covers USDA plant hardiness zones 5a to 7a on the 2023 map, so its coldest areas average −20 to −15 °F on the coldest winter night. Find your zone by ZIP code, or pick a city below for its zone, sunrise and daylight by month.
Illinois hardiness zone map
This is not the official USDA Plant Hardiness Zone Map. Zones are derived from the official 2023 dataset, resampled to about 2 km. Dots mark cities with their own page.
Source: USDA Plant Hardiness Zone Map, 2023. Agricultural Research Service, U.S. Department of Agriculture, planthardiness.ars.usda.gov. Underlying data © PRISM Group, Oregon State University, prism.oregonstate.edu, accessed 2026-08-30.
Zones and daylight by city
| City | Zone | Coldest night | Longest day | Shortest day |
|---|---|---|---|---|
| Chicago | 6a | −10 to −5 °F | 15h 13m | 9h 08m |
| Aurora | 5b | −15 to −10 °F | 15h 13m | 9h 09m |
| Naperville | 5b | −15 to −10 °F | 15h 13m | 9h 09m |
| Joliet | 5b | −15 to −10 °F | 15h 11m | 9h 10m |
| Rockford | 5b | −15 to −10 °F | 15h 16m | 9h 05m |
| Springfield | 6a | −10 to −5 °F | 15h 00m | 9h 21m |
| Elgin | 5b | −15 to −10 °F | 15h 15m | 9h 07m |
| Peoria | 6a | −10 to −5 °F | 15h 06m | 9h 15m |
| Champaign | 6a | −10 to −5 °F | 15h 02m | 9h 19m |
| Bloomington | 6a | −10 to −5 °F | 15h 04m | 9h 17m |
| Evanston | 6a | −10 to −5 °F | 15h 15m | 9h 07m |
Gardening in Illinois?
Your zone says what survives winter. Deconstruct Sun measures how many hours of direct sun your exact spot gets, so you can pick plants that thrive. Free on iPhone.
Questions
What hardiness zones are in Illinois?
Illinois spans USDA zones 5a to 7a on the 2023 map. Among its larger cities, Aurora is coldest (zone 5b) and Chicago is warmest (zone 6a).
How do I find my exact zone in Illinois?
Enter your ZIP code in the hardiness zone lookup on this site. It reads the 2023 USDA data for that ZIP and warns you if you are near a zone boundary.
How much sun do gardens in Illinois get?
In Chicago, an open spot gets up to 15.2 hours of daylight in June but only 9.1 in December. Trees and buildings cut that down, especially in winter. The Deconstruct Sun app measures the real direct-sun hours for one exact spot.