Home › Frost dates › Illinois
Illinois frost dates
Across the 22Illinois weather stations below, the average last spring frost ranges from Apr 2 in Cairo 3N to Apr 30 in Chicago Waukegan. The statewide middle is about Apr 16 for the last spring frost and Oct 21 for the first fall frost. Cairo 3N has the longest growing season, about 212 days. Hardiness zones in these places: 5b, 6a, 6b, 7a.
Frost dates by city
| Place | Zone | Last spring frost | 90% safe after | First fall frost | Frost-free days |
|---|---|---|---|---|---|
| Cairo 3N | 7a | Apr 2 | Apr 17 | Oct 31 | 212 |
| Cahokia Louis | 7a | Apr 8 | Apr 23 | Oct 26 | 201 |
| Lawrenceville | 6b | Apr 8 | Apr 22 | Oct 26 | 201 |
| Carbondale Southern Il | 7a | Apr 9 | Apr 25 | Oct 22 | 196 |
| Chicago Midway | 6a | Apr 11 | Apr 27 | Oct 31 | 203 |
| Belleville Siu Rsch | 6b | Apr 12 | Apr 28 | Oct 20 | 191 |
| Quincy | 6a | Apr 14 | May 1 | Oct 23 | 192 |
| Springfield Capital | 6a | Apr 14 | Apr 29 | Oct 20 | 189 |
| Mattoon Coles | 6a | Apr 15 | Apr 30 | Oct 24 | 192 |
| Chicago Ohare | 6a | Apr 16 | May 1 | Oct 28 | 195 |
| Decatur | 6a | Apr 16 | Apr 30 | Oct 22 | 189 |
| Peoria Gtr Peoria | 6a | Apr 16 | May 4 | Oct 23 | 190 |
| Champaign Willard | 6a | Apr 19 | May 5 | Oct 17 | 181 |
| Chicago Palwaukee | 6a | Apr 19 | May 3 | Oct 26 | 190 |
| Rantoul | 6a | Apr 21 | May 6 | Oct 18 | 180 |
| Champaign 9 Sw | 5b | Apr 23 | May 9 | Oct 13 | 173 |
| Moline Quad | 5b | Apr 24 | May 9 | Oct 18 | 177 |
| Rockford Gtr Rockford | 5b | Apr 24 | May 8 | Oct 17 | 176 |
| West Chicago Dupage | 5b | Apr 25 | May 12 | Oct 19 | 177 |
| Chicago Aurora | 5b | Apr 28 | May 11 | Oct 13 | 168 |
| Shabbona 5 Nne | 5b | Apr 28 | May 13 | Oct 10 | 165 |
| Chicago Waukegan | 6a | Apr 30 | May 16 | Oct 21 | 174 |
Dates are the 50% probability of a 32°F freeze (NOAA 1991–2020 normals); "90% safe after" is the date after which a later spring freeze happens in only 1 year in 10.
When to plant in Illinois
Using the statewide middle dates (last frost Apr 16, first frost Oct 21). Adjust for your town with the table above or the planting calendar.
| Plant | When to plant in Illinois |
|---|---|
| Tomatoes | Apr 23 – May 7 |
| Peas | Mar 5 – Mar 26; fall: Jul 29 – Aug 19 |
| Potatoes | Mar 19 – Apr 9 |
| Green beans | Apr 23 – May 7; fall: Aug 5 – Aug 19 |
| Garlic | Oct 21 – Nov 18 |
| Tulips | Oct 7 – Nov 18 |